EP3215723B1 - Apparatus for monitoring an oil thermostat - Google Patents
Apparatus for monitoring an oil thermostat Download PDFInfo
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- EP3215723B1 EP3215723B1 EP15794465.3A EP15794465A EP3215723B1 EP 3215723 B1 EP3215723 B1 EP 3215723B1 EP 15794465 A EP15794465 A EP 15794465A EP 3215723 B1 EP3215723 B1 EP 3215723B1
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- oil
- temperature
- thermostat
- oil thermostat
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
- F01M11/10—Indicating devices; Other safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M5/00—Heating, cooling, or controlling temperature of lubricant; Lubrication means facilitating engine starting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M5/00—Heating, cooling, or controlling temperature of lubricant; Lubrication means facilitating engine starting
- F01M5/005—Controlling temperature of lubricant
- F01M5/007—Thermostatic control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
- F01M11/10—Indicating devices; Other safety devices
- F01M2011/14—Indicating devices; Other safety devices for indicating the necessity to change the oil
- F01M2011/1446—Indicating devices; Other safety devices for indicating the necessity to change the oil by considering pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
- F01M11/10—Indicating devices; Other safety devices
- F01M2011/14—Indicating devices; Other safety devices for indicating the necessity to change the oil
- F01M2011/1473—Indicating devices; Other safety devices for indicating the necessity to change the oil by considering temperature
Definitions
- the invention relates to a device for monitoring an oil thermostat arranged in an oil circuit of an internal combustion engine.
- the DE 44 26 494 A1 a device for monitoring the cooling system in an internal combustion engine, in which a temperature signal characteristic of the cooling system is generated and the profile of the temperature signal is then evaluated and detected temperature changes per unit of time are compared with plausible values.
- EP 0 736 703 A1 a device for influencing the transmission oil temperature in motor vehicles with a cooling device for cooling the transmission oil, with a heating device for heating the transmission oil and with a valve, the transmission oil temperature being controlled to a predetermined setpoint in one operating state in the form of mixed operation.
- cooling water thermostats are used in the cooling water circuit, but also increasingly oil thermostats in the oil circuit of an internal combustion engine.
- oil thermostats By means of such oil thermostats, the friction can be reduced in specific operating states in order to achieve fuel consumption advantages compared to conventional engines.
- the oil thermostat feeds the oil supplied to it, depending on the oil temperature, either to a flow branch with an oil cooler or to a bypass flow branch bypassing the oil cooler.
- a defective oil thermostat which can no longer direct the oil through the oil cooler, usually results in violent engine damage due to the excessive oil temperature.
- a defective oil thermostat which is designed in its failure behavior to assume the switching state in the event of a loss of function, in which the oil is always routed via the oil cooler in order to prevent rapid damage to the internal combustion engine, on the other hand leads to increased fuel consumption and CO2 emissions in the longer term due to the increased friction.
- the oil thermostat will fail in an undefined state, for example due to contamination (original dirt, sand%), particles or chips, or due to mechanical forces or high pressure peaks that can lead to deformation of the thermostat, which can lead to jamming in any thermostat position.
- hydraulic pressure peaks of up to 60 bar can occur in the oil circuit of today's engines, especially since oil can be very viscous in the event of a cold start.
- a defective water thermostat in the cooling water circuit can usually be recognized by the fact that the operating temperature of the internal combustion engine is no longer reached or is only reached very slowly.
- a defect in the oil thermostat cannot be recognized by the driver, or at least not promptly, since a defective oil thermostat, which always feeds the oil to the oil cooler, usually does not impair the cooling function of the cooling system, but rather the long-term fuel consumption, wear and tear and service life the internal combustion engine. Also by means of the above DE 44 26 494 A1 The device mentioned above only indicates a general malfunction of the cooling system, but not whether the oil thermostat in particular is malfunctioning.
- the object of the invention is in particular to reliably detect a defect or malfunction of the oil thermostat.
- a device for monitoring an oil thermostatic valve arranged in an oil circuit of an internal combustion engine is proposed.
- the oil thermostatic valve monitored by the device (hereinafter referred to as oil thermostat for short) is designed in a manner known per se to feed the oil flow to a bypass flow branch and/or a flow branch having an oil cooler, depending on the temperature of an oil flow supplied to the oil thermostat.
- the oil thermostat typically feeds the oil exclusively to the bypass flow branch when the oil temperature at the oil thermostat, also referred to below as the inlet temperature, is below a first temperature threshold value.
- a first output of the oil thermostat which is assigned to the first flow branch, is closed and is only opened when the first temperature threshold value is exceeded.
- the oil thermostat can also be designed to close the bypass flow branch above a second temperature threshold value, which is preferably above the first temperature threshold value.
- both flow branches are open, with a second output of the oil thermostat assigned to the bypass flow branch gradually closing until the second temperature threshold value is reached.
- the first and second temperature threshold values can also be the same.
- the device for monitoring the oil thermostat includes a sensor device that is designed to determine at least one first parameter, by means of which a current setpoint operation of the oil thermostat can be derived, and to determine at least one second parameter, by means of which a current Actual operation of the oil thermostat can be derived.
- the device also includes an evaluation device which is designed to detect the occurrence of a malfunction of the oil thermostat as a function of the first parameter and the second parameter.
- Target operation of the oil thermostat means normal operation, ie without an assumed malfunction, in which the oil thermostat assumes the desired temperature-dependent operating state, for example the desired temperature-dependent setpoint position or movement of the oil thermostat actuator.
- Actual operation is understood to mean actual operation of the oil thermostat, for example an actual current operating state. If no malfunction occurs, target operation and actual operation match. In the event of a malfunction the actual position of the oil thermostat and/or the actual movement of the actuator of the oil thermostat deviate from the target operation.
- the oil thermostat can be a ring slide oil thermostat or an expansion element oil thermostat, in particular a wax expansion oil thermostat.
- the oil thermostat can also be designed as a mechatronic controller or actuator, with an electronic control unit that controls a mechanical actuator depending on the oil temperature.
- the sensor device is designed to measure the inlet temperature of the oil and in particular its progress over time as the first parameter, for example by means of a temperature sensor in the inlet line to the oil thermostat.
- the inlet temperature is a measure of the oil temperature which is present at the inlet of the oil thermostat and depending on which the oil thermostat assumes a predefined open or closed position with respect to the outlets to the first and second flow branch in target operation. It is particularly advantageous to measure the oil sump temperature as the inlet temperature, since there is usually already a temperature sensor in the oil sump of the oil circuit that can be used.
- the oil sump temperature can be measured, for example, by means of an oil sump temperature sensor that is integrated into the already existing oil level sensor of the oil sump.
- the oil sump temperature essentially corresponds to the oil temperature at the inlet of the oil thermostat. Since the oil temperature of the oil conveyed via an inlet line from the oil sump to the oil thermostat essentially does not change, the inlet temperature can also be determined at any other point along the inlet line using an appropriately arranged temperature sensor.
- the sensor device which measures the inlet temperature as the first parameter, is also designed to measure a second oil temperature downstream of the oil cooler and upstream of the internal combustion engine and to determine a temperature difference ⁇ T from the inlet temperature minus the second oil temperature as the second parameter.
- a temperature sensor can be provided in the first flow branch downstream of the oil cooler and upstream of a combination men arrangement of the first flow branch and the bypass flow branch is arranged.
- the temperature sensor can also be arranged downstream of an oil filter arranged by the internal combustion engine.
- the temperature sensor is preferably designed as a combined pressure and temperature sensor, which is provided in one structural unit. Another advantageous option is to integrate the temperature sensor into an oil filter head.
- the first outlet of the oil thermostat to the cooler should actually be closed in this case due to the low inlet temperature according to target operation.
- the temperature difference ⁇ T is greater than a first threshold value, it can be concluded that oil cooling is taking place and the oil must therefore have flowed through the flow branch with the cooler, and the thermostat must therefore be malfunctioning.
- This first threshold is set as a function of the drop in oil temperature (cooling capacity of the oil cooler) generated by the oil cooler.
- the first threshold value should, for example, be greater than usual fluctuations in the oil temperature in the area between the oil sump and the internal combustion engine that are not caused by the oil cooler, but somewhat smaller than the average cooling capacity of the oil cooler.
- the specified reaction time takes into account a time-delayed behavior of the oil thermostat and represents a time until the resulting temperature difference ⁇ T downstream of the oil thermostat should have set itself after a change in the switching position of the oil thermostat.
- the response time depends on the design of the oil thermostat and the position of the measuring point for the second temperature and can e.g. B. be determined experimentally.
- the occurrence of a malfunction of the oil thermostat can also be detected when the inlet temperature is above the first temperature threshold, at least the specified response time has passed since the inlet temperature is above the first temperature threshold, and the temperature difference ⁇ T is less than a second threshold .
- the inlet temperature is above the first temperature threshold value, the oil flow fed to the oil thermostat would then have to be fed to the oil cooler. If this is not the case, this can again be determined using the temperature difference, which is smaller than when the oil is cooled by the oil cooler.
- the second threshold value can, for example, be set slightly below the differential temperature ⁇ T normally caused by the cooler.
- the occurrence of a malfunction of the oil thermostat can also be detected if, after the inlet temperature has exceeded the first temperature threshold value, a gradient, in particular an increase in the temperature difference ⁇ T, is slower than a specified setpoint increase in the temperature difference.
- the evaluation device thus evaluates the course of the differential temperature over time and can compare this with a stored target increase in the temperature differential.
- a particular advantage of this variant is that the evaluation of the increase in the temperature difference can be used as an early indicator of an incipient malfunction of the oil thermostat. Investigations within the scope of the invention have shown that before a complete malfunction of the oil thermostat, its actuator shows the beginning of jamming or hooking, so that it does not open gradually, but moves relatively late. This can be recognized by a delayed increase in the differential temperature.
- the aforementioned threshold values can be selected as a function of the engine speed, such that larger threshold values are set at a higher current engine speed. This takes into account the fact that as the engine speed increases, the cooling capacity of the oil cooler increases and thus the expected value of the temperature difference.
- the sensor device is designed such that the second parameter is an oil pressure profile, in particular a time profile of the oil pressure, by means of a pressure sensor at a pressure measuring point to be measured, which is arranged downstream of the first output of the oil thermostat and upstream of the internal combustion engine.
- the evaluation device is designed to detect a malfunction of the oil thermostat if the measured time profile of the oil pressure shows no pressure deflection in the form of a negative or positive peak in a range of the inlet temperature that lies between the first oil temperature threshold value and the aforementioned second temperature threshold value .
- a pressure deflection corresponds to a peak-shaped pressure change whose peak height is greater than a predetermined value.
- This predetermined value for detecting a pressure ripple can be experimentally determined oil circuit-specifically, such that pressure ripples that exceed this value do not result from normal pressure fluctuations, but from a changed flow resistance downstream of the oil thermostat corresponding to the at least partially open first and second flow branch.
- a particularly advantageous variant of this embodiment provides that the pressure measuring point or the pressure sensor for measuring the time profile of the oil pressure is arranged in the first flow branch between the first outlet of the oil thermostat and the oil cooler and that the pressure deflection is a negative peak.
- the expected pressure deflection in target operation is a positive peak and the peak height.
- the inlet temperature of the oil can be measured as the first parameter, with the oil sump temperature preferably being measured as the inlet temperature.
- the target operating status of the oil thermostat can be derived directly from the current inlet temperature, since the actuator of the oil thermostat assumes the specified setting positions depending on the inlet temperature.
- the cooling water temperature can be used since the curves of the oil temperature and the cooling water temperature are correlated with one another in target operation.
- a profile of the oil temperature in the supply line can thus be derived from the cooling water temperature, from which in turn the target operation of the oil thermostat can be derived.
- operating states of the vehicle can be used.
- An example of this is the operating state when the vehicle performs a cold start or when driving under full load.
- the oil inlet temperature is below the first temperature threshold value, so that the first flow branch to the oil cooler would have to be closed during normal operation.
- this flow branch is usually open if there is no defect.
- a further possibility of the implementation according to the invention provides, for example, for a gradient of an inlet temperature of the oil to be determined as the second parameter.
- a gradient of the oil sump temperature is preferably determined for this purpose.
- the evaluation device is designed to determine a predetermined setpoint characteristic curve of the gradient of the inlet temperature that is stored in the memory of the evaluation device as a function of the determined value of the first parameter and to detect a malfunction of the oil thermostat if the measured gradient of the inlet temperature is not within specified limits agrees with the target characteristic.
- an operating state of the vehicle is determined as the first parameter. For example, if the vehicle drives up an incline at full load, this results in a known increase in temperature in the oil sump, which was previously determined experimentally and stored in the evaluation device in the form of a characteristic curve. If the evaluation device recognizes driving under full load on the basis of the specific operating state, the evaluation device compares the measured rise in temperature of the inlet temperature with the previously stored characteristic curve for driving under full load. If the current temperature increase in the oil inlet temperature determined using the second parameter deviates from the previously stored temperature increase according to the characteristic curve, a malfunction of the oil thermostat can in turn be derived from this.
- the sensor device is designed to detect a position and/or a movement of an actuator of the oil thermostat as the second parameter.
- the evaluation device is designed to detect the malfunction of the oil thermostat based on the detected position and/or movement of the actuator by comparing the detected position and/or movement of the actuator with the expected position and/or movement according to the depending on the first Parameter specific target operation is compared.
- the malfunction of the oil thermostat can become known if no movement of the actuator is detected in a predetermined oil temperature range or cooling water temperature range in which the actuator would have to move.
- the malfunction of the oil thermostat can be detected when, during a cold start, the actuator is in a position in which the first output is open and/or when the actuator is in a position in which the first output is closed when driving under full load .
- a displacement sensor can be provided, which is mechanically coupled in terms of movement to the actuator.
- the displacement sensor can have a coupling rod which is coupled in terms of movement to the actuator of the oil thermostat.
- the sensor device is designed as an electrical oscillating circuit with a coil, with the coil being arranged from the outside on or near the oil thermostat in such a way that a movement of the Actuator of the oil thermostat changes the inductance of the coil and thus an oscillation frequency of the oscillating circuit.
- the sensor device can have a transmitter coil and a receiver coil, which are each arranged on opposite sides from the outside on or in the vicinity of the oil thermostat, so that a movement of the actuator of the oil thermostat changes a signal induced by the transmitter coil in the receiver coil.
- the advantage of the latter two variants compared to a mechanical coupling with the actuator is that there is no contact with the thermostatically controlled medium (oil) and no additional sealing elements are required, as would be necessary in the case of a coupling rod.
- Another advantage is that the monitoring system element in the form of the sensor device with at least one coil has a significantly longer average service life than the element to be monitored (oil thermostat) and can therefore monitor the oil thermostat for the entire service life of the vehicle.
- the mobile test device also includes fastening means in order to temporarily arrange the sensor device outside on or in the vicinity of the oil thermostat for a measurement process. This means that the oil thermostats of vehicles that are not factory-equipped with a monitoring device for the oil thermostat can be checked later with little maintenance.
- the sensor device is designed as a circuit integrated into the oil thermostat, which is designed to detect a position and/or movement of the actuator of the oil thermostat by means of integrated switching contacts.
- the circuit can be designed in such a way that it monitors the end positions of the valve plate of the oil thermostat using appropriate switch contacts.
- the integrated circuit is also designed in such a way that it draws its supply energy from the oil heat by means of an energy harvesting circuit and transmits a measurement signal wirelessly, preferably by means of near-field radio transmission, to the evaluation device.
- a benefit of this Another variant is that no additional sealing elements have to be provided for attaching the sensor device, since the integrated circuit is provided inside the oil thermostat without having a mechanical connection to the outside.
- a further possibility for designing the sensor device provides for arranging a temperature sensor at a measuring point which is arranged in the first flow branch between the oil thermostat and the oil cooler.
- the oil temperature measured in this way downstream of the first output of the oil thermostat and before the oil cooler can be determined as the first parameter of the sensor device, since the temperature approximately corresponds to the inlet temperature.
- the target operation of the oil thermostat can thus be derived from the measured temperature.
- the temperature measurement immediately after the first output of the oil thermostat can also be used to determine the second parameter.
- a malfunction of the oil thermostat can be detected by the evaluation device, for example, if the measured oil temperature remains essentially unchanged at this point after the first output should have opened or closed according to the determined first variable.
- the present invention can also be used to monitor two or more thermostats connected in parallel, for example a small and a large thermostat, which have either the same or different temperature settings and in which the oil discharge supplies different pressure oil consumers.
- figure 1 shows schematically the components of an oil circuit 1, only that part of the oil circuit being shown which is arranged in the flow path between the oil sump and the internal combustion engine.
- an oil pan 2 is arranged, in which the oil sump 2a is arranged, the fill level of which is monitored with an oil level probe 3 .
- the oil from the oil sump 2a is fed to the flow inlet 11 of an oil thermostat 10 via an inlet line 5 .
- an oil pump 6, a pressure relief valve 7 and a return check valve 8 are arranged in the supply line 5.
- the oil thermostat 10 is designed, for example, as a ring slide oil thermostat or wax expansion oil thermostat and contains an actuator that moves into a specific position depending on the oil temperature present at the input 11 of the oil thermostat 10 (inlet temperature T2).
- the oil supplied to the oil thermostat is connected via the line 9 to a control input of the oil thermostat valve 10 and, for example in the case of a wax expansion thermostat, depending on the oil temperature, causes the actuator of the oil thermostat to heat up and thus expand, or to cool down and contract in itself , so that the valve plates of the actuator are moved to open or close a first output 12 of the oil thermostat 10 and to close or open the second output 13 of the oil thermostat 10 .
- the outlet 12 of the oil thermostat 10 that connects the inlet line 5 to a first flow branch 17 in which an oil cooler 16 is arranged is closed. Instead, the oil is fed via the second outlet 13 of the oil thermostat 10 to a second bypass flow branch 18 which bypasses the oil cooler 16 . If, on the other hand, the inlet temperature T2 is greater than a second temperature threshold value T1*, which is above the value T1, the second outlet 13 is completely closed and the first outlet 12 is open, so that the oil flows exclusively via the oil cooler 16. In the area between T1 and T1*, the first exit is open and the second exit is only partially closed.
- the first flow branch 17 and the second flow branch 18 are brought together after the oil cooler 16 to form a common flow section 19 .
- the oil then flows through an oil filter 20, which also has a filter service valve 21 and a filter bypass valve 22. Downstream of the oil filter 20, there is a siphon 23 in the oil filter head and an oil pressure sensor 25 integrated into the oil filter head shown) supplied.
- a device for monitoring the oil thermostat is also provided in order to be able to detect a malfunction of the oil thermostat.
- the device includes a sensor device that is designed to determine at least one first parameter, by means of which or from which a current operation of the oil thermostat 10 can be derived.
- the sensor device can comprise a temperature sensor 4, for example, which determines the oil sump temperature as the first parameter.
- the oil sump temperature T2 essentially corresponds to the oil temperature which is present at the oil thermostat 10 and which determines the position of the actuator during target operation.
- the oil sump temperature sensor 4 can be integrated into the oil level sensor 3 and provided as a so-called combined sensor.
- the target operating state of the oil thermostat 10 can be derived directly from the determined oil sump temperature will.
- the first outlet 12 to the first flow branch 17, comprising the oil cooler 16 is closed at oil sump temperatures T2 ⁇ T1.
- the flow through the first flow branch 17 is open and the bypass flow branch 18 is also still partially open.
- the flow through the first flow branch 17 is fully open and the second outlet 13 and thus the bypass flow branch 18 are completely closed.
- Exemplary values for T1 are in the range of 95 degrees to 105 degrees and for T1* around 120 degrees.
- the sensor device of the device for monitoring the oil thermostat is also designed to determine a second parameter, by means of which a current actual operation of the oil thermostat can be derived.
- the temperature sensor 14b can be used, which is arranged downstream of the oil cooler 16 in the first flow branch 17 before this is combined with the bypass flow branch 18 .
- a second oil temperature T3 downstream of the oil cooler 16 can be measured with this temperature sensor 14b. From this second oil temperature T3, a temperature difference ⁇ T can then be determined from the inlet temperature T2 minus the second oil temperature T3, which can be used to determine whether the actual operation of the oil thermostat 10 matches the expected target operation.
- figure 2 shows a time profile of the inlet temperature T2, which was determined using the sensor 4, and a time profile of the second oil temperature T3, which was measured with the sensor 14b downstream of the oil cooler 16.
- the dashed line T1 indicates the threshold of the opening temperature T1.
- the inlet temperature T2 is lower than the opening temperature T1 of the first outlet 12 of the oil thermostat 10.
- oil should not flow through the first flow branch since the first outlet 12 would have to be closed in this case.
- figure 2 shows a temperature profile that occurs when the oil thermostat 10 malfunctions, e.g. B. in the event of a defect in the actuator, the oil cooler 16 also at inlet temperatures T2 ⁇ T1 of oil flows through. As a result, the oil is cooled down by the amount ⁇ T by the oil cooler 16 .
- An evaluation unit 40 connected to the sensor device 4, 14b via a signal input line 41 now uses the determined measured values to check whether the determined temperature difference ⁇ T has a value that is expected according to a target operation, or whether there is a malfunction in the oil thermostat 10.
- the evaluation unit 40 checks whether the temperature difference ⁇ T from the inlet temperature T2 minus the second oil temperature T3 is less than a predetermined first temperature threshold value ⁇ T1.
- a malfunction of the oil thermostat is detected when the inlet temperature is below the first temperature threshold, at least a predetermined response time Z1 has passed since the inlet temperature is below the first temperature threshold T1, and the temperature difference ⁇ T from the inlet temperature minus the second oil temperature is greater than a first threshold value ⁇ T1 is.
- the first threshold ⁇ T1 is set depending on the drop in oil temperature (cooling capacity of the oil cooler) generated by the oil cooler.
- the first threshold value should, for example, be greater than usual fluctuations in the oil temperature in the area between the oil sump and the internal combustion engine that are not caused by the oil cooler, but somewhat smaller than the average cooling capacity of the oil cooler.
- the specified response time Z1 takes into account a time-delayed behavior of the oil thermostat and represents a time after a change in the switching position of the oil thermostat, until the resulting temperature difference ⁇ T downstream of the oil thermostat should have set itself.
- the response time depends on the design of the oil thermostat and the position of the measuring point for the second temperature and can e.g. B. be determined experimentally.
- the evaluation device 40 If the evaluation device 40 detects a malfunction of the oil thermostat 10, it outputs a warning signal via the output line 42, which z. B. is output via a display device in the cockpit of the vehicle.
- figure 3 shows the temperature curve in the event of a malfunction of oil thermostat 10, in which oil thermostat 10 does not go into a position in which first outlet 12 is open and oil flows through oil cooler 16, despite an inlet temperature T1 that is greater than first temperature threshold value T1 becomes.
- this is in figure 3 recognizable from the fact that the temperature difference ⁇ T from the inlet temperature minus the second temperature T3, which is measured by the temperature sensor 14b, is less than a predetermined second temperature threshold value ⁇ T2.
- the threshold value ⁇ T2 is selected such that a temperature difference ⁇ T is always greater than the threshold value ⁇ T2 when the oil flows through the oil cooler 16.
- the small difference between the temperature T3 and the inlet temperature T2 indicates that there must be a defective oil thermostat.
- the fact that the temperature profile T3 is slightly below the temperature profile T2 results from the fact that the bypass flow branch 18 is spatially arranged in the vicinity of the oil cooler 16 and as a result radiates some cooling capacity from the oil cooler 16 and also the oil in the bypass flow branch 18 cools slightly.
- the differential temperature ⁇ T is again evaluated only after a predetermined reaction period Z1 has elapsed.
- figure 4 illustrates a further possibility of detecting a malfunction according to an embodiment variant.
- the first temperature threshold value is in turn denoted by the dashed line T1, below which the first output is closed and above which the first output 12 is open.
- the course of the inlet temperature T2 over time is in turn measured with the temperature sensor 4 in the oil sump of the oil circuit 1 .
- FIG 4 shows the course of the inlet temperature T2 over time, starting with a cold start of the vehicle.
- the cold start range is represented by the area marked K.
- the temperature range Z2 indicates the thermostat opening range, which begins after the inlet temperature T2 exceeds the opening temperature T1.
- the subsequent area B marks an area of persistence at operating temperature.
- the dashed line which is identified by the reference character T3, indicates the course of the oil temperature, which is measured in front of the internal combustion engine but downstream of the oil cooler 16, for example with the temperature sensor 24.
- the oil cooler In the cold start range K below the temperature threshold value T1, the oil cooler is closed, as expected, so that the temperature T3 follows the course of the inlet temperature T2 and is only slightly below its value, due to the above-mentioned radiation effects of the cooler 16.
- the actuator of the oil thermostat 10 should gradually open the first output 12 .
- the course would result that is marked with the dash-dotted line T3.2.
- a temperature profile over time is also shown, which is identified by the dashed line T3.1 and which can be measured at the sensor 24 if the oil thermostat 10 is slightly defective.
- the temperature gap between inlet temperature T2 and temperature T3.1 after the oil cooler does not diverge as quickly as according to curve T3.2, although the temperature difference ⁇ T from point B1 is again the same for both temperature curves.
- the temperature profile T3.1 can be observed in an oil thermostat 10, the actuator of which already shows the beginning of jamming behavior or a slight snagging, so that the actuator initially "jams” in the area Z2 and only becomes a "tears loose” at a later point in time and suddenly jumps into the completely open position.
- Such a jamming behavior indicates a future complete jamming of the oil thermostat 10 .
- the evaluation device 40 recognizes such a malfunction from the rise in the temperature difference ⁇ T if the rise in the temperature difference is slower than a predefined setpoint rise in the temperature difference. In other words, the course of the temperature difference over time is recorded. If this is less than a predetermined target increase, which is stored in the evaluation device 40 in the form of an experimentally determined characteristic curve, a malfunction of the oil thermostat 10 is detected.
- One possibility for determining a malfunction is to specify a minimum value for the temperature difference between T2 and T3, which must be reached after the opening temperature T1 has been exceeded after a specified reaction time has elapsed. If the measured temperature difference is less than the minimum value for the temperature difference after the specified response time has elapsed, there is a malfunction.
- thermostats can be subject to a set temperature tolerance even when they are new. In principle, this can be taken into account in the evaluation unit, for example with a continuous increase in wear on the thermostat, the defined temperature limits T1 and T1*, which lead to a movement of the actuating mechanism, are increasingly frequently torn or shifted. Calculation sequences can therefore be active in the evaluation unit and characteristic diagrams can be stored which define the temperature limits T1 and T1* and/or the threshold values ⁇ T1 and ⁇ T2 for the monitoring variants Figures 2 to 4 due to wear and tear, so that the replacement or defect of the thermostat is only signaled when there is no doubt that the intended operation of the engine can no longer be guaranteed.
- figure 5 1 illustrates a further possibility according to the invention for detecting a defect situation in the oil thermostat 10.
- the sensor device is set up here to measure a pressure profile over time by means of a pressure sensor 15 which is arranged in the first flow branch 17 between the first outlet 12 of the oil thermostat 10 and the oil cooler 16. Furthermore, the sensor device in turn determines the course of the inlet temperature T2 over time, for example by means of the temperature sensor 4.
- the dotted lines indicate the area between the two temperature thresholds T1 and T1* of the oil thermostat.
- the first is Output 12 closed when the inlet temperature T2 is below the value T1.
- the first outlet is fully open and the second outlet 13 is fully closed.
- the first outlet 12 is open and the second outlet 13 is only partially closed, so that oil flows both through the first flow branch 17 and through the second flow branch 18.
- the curve P shows the pressure profile over time measured by the pressure sensor 15 .
- the pressure profile P describes the profile of a normally functioning oil thermostat 10. In the temperature ranges of the inlet temperature T2 below T1, the pressure profile essentially has the value P1 and in the areas in which the inlet temperature is above the value T1*, the value P2. In this case, P2 is essentially slightly higher than P1, since the oil cooler 16 has a higher flow resistance than the bypass line 18 and thus leads to increased pressure values P2. In the transition area between T1 and T1*, however, both lines are at least partially open, so that the flow resistance is lowest in this area. This leads to a negative pressure peak ⁇ P in the area of the pressure curve between T1 and T1*.
- the pressure profile can also be measured, for example, with the pressure sensor 25, which is arranged after the oil filter.
- the target pressure curve differs from that in figure 5 shown in that a positive peak is measured in the transition areas between T1 and T1*, since the oil flow rate at the measuring point of the pressure sensor 25 is greatest in this area. Will again be analogous to figure 5 If no positive peak is measured in this area in the transition area, a malfunction can again be concluded.
- Temperature sensors 4, 14a, 14b and 24 and pressure sensors 15 and 25 have all been placed simultaneously in figure 1 shown. However, it is emphasized that, depending on the embodiment variant of the sensor device, only some of these sensors must be present in the oil circuit 1, e.g. For example, depending on the variant, it may be sufficient to use the temperature sensor 4 to determine the inlet temperature and to use the sensor 14b or 24 to determine the differential temperature. Instead of the temperature sensors 14b and 24, only one pressure sensor 15 or 25 can also be provided, for example, if the defect is detected on the basis of the pressure profile P and not on the basis of the differential temperature ⁇ T.
- the oil thermostat 10 the oil cooler 16, the oil filter 20, the filter service valve 21, the filter bypass valve 22, the oil siphon 23 and the sensors 14a, 15, 23 and 24 are structurally integrated in an oil module which is indicated by the dot-dash line 27 is shown.
- FIG. 6 a part of an oil circuit is first shown again, now in a schematic constructive representation.
- the reference numeral 2 again denotes the oil pan and the reference numeral 6 denotes the oil pump, which pumps oil from the oil pan 2 and feeds it to the oil thermostat 10 .
- the reference numeral 12 in turn designates the first outlet of the oil thermostat 10 which supplies oil to the oil cooler 16 via the first flow branch 17 .
- the reference numeral 13 in turn designates the second outlet of the oil thermostat 10 via which oil can be fed to the bypass flow branch 18 .
- cooling water circuit is shown with a cooling water supply line 70, an area 71 which forms part of the oil cooler functionality and in which the cooling water flows around the meandering oil line of the oil cooler 16, and a line section 72 via which the cooling water heated in the oil cooler 16 is discharged .
- the return of the oil after passing through the area of the internal combustion engine back to the oil pan 2 is only indicated in a highly schematic manner by the reference number 73 .
- the function of the oil thermostat can also be monitored directly by means of a displacement sensor 81, in which a coupling rod 82 is directly mechanically coupled to the actuator 10b of the oil thermostat 10 for movement.
- the movement of the actuator 10b of the oil thermostat 10 is thus detected directly by the displacement sensor 81 and output from the displacement sensor 81 to the evaluation device 40 via an output line 83 .
- the evaluation device 40 is designed to diagnose a malfunction if the actuator 10b does not move when the opening temperature T1 is exceeded or generally when the temperature range between T1 and T1* is reached.
- figure 6 10 illustrates yet another embodiment variant as an alternative to using the displacement sensor 81.
- an integrated circuit 80 can be provided inside the oil thermostat 10, which is designed to detect a position and/or movement of the actuator 10b of the oil thermostat 10 by means of integrated switching contacts.
- a switching contact of the switching circuit 80 is arranged at one end of the actuator 10b and detects a movement of a valve disc 10c of the actuator 10b when it moves to close or open an output of the oil thermostat 10, and thereby in contact or out of contact the switching contact.
- the integrated circuit 80 is designed to extract its supply energy from the oil heat by means of a so-called energy harvesting circuit. Such energy harvesting circuits are known per se from the prior art. Furthermore, the switching circuit 80 is designed to transmit its measurement signals wirelessly to the evaluation device 40 by means of a near-field radio transmission. As a result, the integrated circuit can be completely encapsulated by the oil thermostat 10 so that no additional sealing elements, signal lines or power supply lines have to be provided.
- the sensor device comprises an electrical oscillating circuit with a coil 76, the coil 76 being arranged on the housing 10a of the oil thermostat 10 from the outside.
- the coil is arranged in such a way that a movement of the actuator 10b of the oil thermostat 10, which is designed to be magnetic, changes the inductance of the coil 76 and thus an oscillation frequency of the oscillating circuit.
- the measurement signal of the resonant circuit with the coil 76 is transmitted to the evaluation device 40 via a signal line 76a.
- the evaluation device 40 can in turn monitor the function of the oil thermostat 10 by using one of the aforementioned options for determining a first parameter from which the target operation of the oil thermostat can be derived, determining when an actuator of the oil thermostat 10 should move. Based on the detected frequency of the oscillating circuit, the evaluation device 40 can also determine whether an expected movement of the actuator 10b actually takes place at the expected time or whether, for example, the actuator is jammed and therefore no change in the oscillation frequency can be measured.
- a further possibility for non-contact detection of the movement of the actuator 10b of the oil thermostat 10 is to design the sensor device in such a way that a transmitter coil 74 and a receiver coil 75 are arranged on opposite sides from the outside of the oil thermostat housing 10b or in its vicinity.
- a movement of the magnetic actuator 10b of the oil thermostat 10 then changes a signal induced by the transmitter coil 74 in the receiver coil 75, which signal is transmitted to the evaluation device 40 via a signal line 75a.
- This change can in turn be diagnosed by the evaluation device 40 so that the presence of such a change in the signal received by the receiver coil correspondingly indicates a normal function of the oil thermostat. No such change will occur at the expected time according to the target operation of the signal received with the receiver coil is measured, the oil thermostat 10 is malfunctioning.
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Description
Die Erfindung betrifft eine Vorrichtung zur Überwachung eines in einem Ölkreislauf einer Brennkraftmaschine angeordneten Ölthermostats.The invention relates to a device for monitoring an oil thermostat arranged in an oil circuit of an internal combustion engine.
Aus dem Stand der Technik ist es bekannt, die Funktion eines Kühlsystems einer Brennkraftmaschine, das dafür zu sorgen hat, dass die Motortemperatur nicht zu hoch wird, zu überwachen. So offenbart beispielsweise die
Ferner offenbart das Dokument
Aus der Praxis ist es ferner bekannt, dass nicht nur Kühlwasserthermostate im Kühlwasserkreislauf, sondern zunehmend auch Ölthermostate im Ölkreislauf einer Brennkraftmaschine eingesetzt werden. Mittels derartiger Ölthermostate kann die Reibleistung in spezifischen Betriebszuständen reduziert werden, um dadurch Kraftstoffverbrauchsvorteile gegenüber konventionellen Motoren zu realisieren. Hierfür führt das Ölthermostat das ihm zugeführte Öl in Abhängigkeit von der Öltemperatur wahlweise einem Strömungszweig mit einem Ölkühler oder einem den Ölkühler umgehenden Bypass-Strömungszweig zu. Ein defektes Ölthermostat, das das Öl nicht mehr über den Ölkühler leiten kann, hat in der Regel Motorgewaltschäden bedingt durch die zu hohe Öltemperatur zur Folge. Ein defektes Ölthermostat, das in seinem Ausfallverhalten ausgelegt ist, bei einem Funktionsverlust den Schaltzustand einzunehmen, bei dem das Öl stets über den Ölkühler geleitet wird, um so eine rapide Beschädigung der Brennkraftmaschine zu verhindern, führt andererseits aufgrund der erhöhten Reibleistung längerfristig zu einem erhöhten Kraftstoffverbrauch und CO2-Ausstoß. Darüber hinaus besteht die Möglichkeit, dass ein Ausfall des Ölthermostats mit undefiniertem Zustand erfolgt, beispielsweise bedingt durch Verschmutzung (Urschmutz, Sand ...), Partikel oder Späne, oder bedingt durch mechanische Kräfte bzw. hohe Druckspitzen, die zu Verformungen am Thermostat führen können, die in der Folge zu Klemmungen in jeder beliebigen Thermostatstellung führen können. Hierbei ist zu erwähnen, dass im Ölkreislauf bei heutigen Motoren hydraulische Druckspitzen bis 60 bar auftreten können, insbesondere da im Kaltstartfall Öl sehr zähflüssig sein kann.It is also known from practice that not only cooling water thermostats are used in the cooling water circuit, but also increasingly oil thermostats in the oil circuit of an internal combustion engine. By means of such oil thermostats, the friction can be reduced in specific operating states in order to achieve fuel consumption advantages compared to conventional engines. For this purpose, the oil thermostat feeds the oil supplied to it, depending on the oil temperature, either to a flow branch with an oil cooler or to a bypass flow branch bypassing the oil cooler. A defective oil thermostat, which can no longer direct the oil through the oil cooler, usually results in violent engine damage due to the excessive oil temperature. A defective oil thermostat, which is designed in its failure behavior to assume the switching state in the event of a loss of function, in which the oil is always routed via the oil cooler in order to prevent rapid damage to the internal combustion engine, on the other hand leads to increased fuel consumption and CO2 emissions in the longer term due to the increased friction. There is also the possibility that the oil thermostat will fail in an undefined state, for example due to contamination (original dirt, sand...), particles or chips, or due to mechanical forces or high pressure peaks that can lead to deformation of the thermostat, which can lead to jamming in any thermostat position. It should be mentioned here that hydraulic pressure peaks of up to 60 bar can occur in the oil circuit of today's engines, especially since oil can be very viscous in the event of a cold start.
Ein defektes Wasserthermostat im Kühlwasserkreislauf kann in der Regel bereits daran erkannt werden, dass die Betriebstemperatur der Brennkraftmaschine nicht mehr oder nur noch sehr schleppend erreicht wird. Ein Defekt des Ölthermostats ist dagegen für den Fahrer nicht oder zumindest nicht zeitnah erkennbar, da ein defektes Ölthermostat, welches das Öl stets dem Ölkühler zuführt, in der Regel die Kühlfunktion des Kühlsystems nicht beeinträchtigt, sondern stattdessen den längerfristigen Kraftstoffverbrauch, den Verschleiß und die Lebensdauer der Brennkraftmaschine. Auch mittels der in der vorstehend genannten
Es ist somit eine Aufgabe der Erfindung, eine Vorrichtung zur Überwachung eines in einem Ölkreislauf einer Brennkraftmaschine angeordneten Ölthermostats bereitzustellen, mit dem Nachteile herkömmlicher Techniken vermieden werden können. Die Aufgabe der Erfindung ist es insbesondere, einen Defekt oder eine Fehlfunktion des Ölthermostats zuverlässig zu erkennen.It is therefore an object of the invention to provide a device for monitoring an oil thermostat arranged in an oil circuit of an internal combustion engine, with which disadvantages of conventional techniques can be avoided. The object of the invention is in particular to reliably detect a defect or malfunction of the oil thermostat.
Diese Aufgabe wird durch eine Vorrichtung mit den Merkmalen des Hauptanspruchs gelöst. Vorteilhafte Ausführungsformen und Anwendungen der Erfindung sind Gegenstand der abhängigen Ansprüche und werden in der folgenden Beschreibung unter teilweiser Bezugnahme auf die Figuren näher erläutert.This object is achieved by a device having the features of the main claim. Advantageous embodiments and applications of the invention are the subject matter of the dependent claims and are explained in more detail in the following description with partial reference to the figures.
Erfindungsgemäß wird eine Vorrichtung zur Überwachung eines in einem Ölkreislauf einer Brennkraftmaschine angeordneten Ölthermostatventils vorgeschlagen.According to the invention, a device for monitoring an oil thermostatic valve arranged in an oil circuit of an internal combustion engine is proposed.
Das von der Vorrichtung überwachte Ölthermostatventil (nachfolgend kurz als Ölthermostat bezeichnet) ist in an sich bekannter Weise ausgebildet, in Abhängigkeit von einer Temperatur eines dem Ölthermostat zugeführten Ölstroms den Ölstrom einem Bypass-Strömungszweig und/oder einem einen Ölkühler aufweisenden Strömungszweig zuzuführen. Hierbei führt das Ölthermostat das Öl typischerweise ausschließlich dem Bypass-Strömungszweig zu, wenn die Öltemperatur am Ölthermostat, nachfolgend auch als Zulauftemperatur bezeichnet, unterhalb eines ersten Temperaturschwellenwerts liegt. In diesem Temperaturbereich ist ein dem ersten Strömungszweig zugeordneter erster Ausgang des Ölthermostats verschlossen, welcher erst bei Überschreiten des ersten Temperaturschwellenwerts geöffnet wird. Das Ölthermostat kann ferner ausgebildet sein, den Bypass-Strömungszweig oberhalb eines zweiten Temperaturschwellenwerts, der vorzugsweise oberhalb des ersten Temperaturschwellenwerts liegt, zu verschließen. In dem Temperaturbereich zwischen den beiden Temperaturschwellenwerten sind beide Strömungszweige geöffnet, wobei ein dem Bypass-Strömungszweig zugeordneter zweiter Ausgang des Ölthermostats schrittweise bis zum Erreichen des zweiten Temperaturschwellenwerts schließt. Der erste und zweite Temperaturschwellenwert können je nach Ausführung des Ölthermostats auch gleich groß sein.The oil thermostatic valve monitored by the device (hereinafter referred to as oil thermostat for short) is designed in a manner known per se to feed the oil flow to a bypass flow branch and/or a flow branch having an oil cooler, depending on the temperature of an oil flow supplied to the oil thermostat. In this case, the oil thermostat typically feeds the oil exclusively to the bypass flow branch when the oil temperature at the oil thermostat, also referred to below as the inlet temperature, is below a first temperature threshold value. In this temperature range, a first output of the oil thermostat, which is assigned to the first flow branch, is closed and is only opened when the first temperature threshold value is exceeded. The oil thermostat can also be designed to close the bypass flow branch above a second temperature threshold value, which is preferably above the first temperature threshold value. In the temperature range between the two temperature threshold values, both flow branches are open, with a second output of the oil thermostat assigned to the bypass flow branch gradually closing until the second temperature threshold value is reached. Depending on the design of the oil thermostat, the first and second temperature threshold values can also be the same.
Gemäß allgemeinen Gesichtspunkten der Erfindung umfasst die Vorrichtung zur Überwachung des Ölthermostats eine Sensoreinrichtung, die ausgebildet ist, wenigstens einen ersten Parameter zu bestimmen, mittels dessen ein aktueller Soll-Betrieb des Ölthermostats ableitbar ist, und wenigstens einen zweiten Parameter zu bestimmen, mittels dessen ein aktueller Ist-Betrieb des Ölthermostats ableitbar ist. Die Vorrichtung umfasst ferner eine Auswerteeinrichtung, die ausgebildet ist, in Abhängigkeit von dem ersten Parameter und dem zweiten Parameter ein Auftreten einer Fehlfunktion des Ölthermostats zu erkennen.According to general aspects of the invention, the device for monitoring the oil thermostat includes a sensor device that is designed to determine at least one first parameter, by means of which a current setpoint operation of the oil thermostat can be derived, and to determine at least one second parameter, by means of which a current Actual operation of the oil thermostat can be derived. The device also includes an evaluation device which is designed to detect the occurrence of a malfunction of the oil thermostat as a function of the first parameter and the second parameter.
Unter einem Soll-Betrieb des Ölthermostats wird ein Normal-Betrieb, d. h. ohne angenommene Fehlfunktion, verstanden, in dem das Ölthermostat den erwünschten temperaturabhängigen Betriebszustand annimmt, beispielsweise die erwünschte temperaturabhängige Soll-Stellung oder Bewegung des Stellglieds des Ölthermostats. Unter dem Ist-Betrieb wird ein tatsächlicher Betrieb des Ölthermostats verstanden, beispielsweise ein tatsächlicher aktueller Betriebszustand. Tritt keine Fehlfunktion auf, stimmen Soll-Betrieb und Ist-Betrieb überein. Bei einer Fehlfunktion können die Ist-Stellung des Ölthermostats und/oder die Ist-Bewegung des Stellglieds des Ölthermostats von dem Soll-Betrieb abweichen.Target operation of the oil thermostat means normal operation, ie without an assumed malfunction, in which the oil thermostat assumes the desired temperature-dependent operating state, for example the desired temperature-dependent setpoint position or movement of the oil thermostat actuator. Actual operation is understood to mean actual operation of the oil thermostat, for example an actual current operating state. If no malfunction occurs, target operation and actual operation match. In the event of a malfunction the actual position of the oil thermostat and/or the actual movement of the actuator of the oil thermostat deviate from the target operation.
Das Ölthermostat kann ein Ringschieberölthermostat oder ein Dehnstoffelementölthermostat, insbesondere ein Wachsausdehnungsölthermostat, sein. Das Ölthermostat kann ferner als mechatronischer Steller bzw. Aktuator ausgeführt sein, mit einer elektronischen Steuereinheit, die in Abhängigkeit der Öltemperatur ein mechanisches Stellglied ansteuert.The oil thermostat can be a ring slide oil thermostat or an expansion element oil thermostat, in particular a wax expansion oil thermostat. The oil thermostat can also be designed as a mechatronic controller or actuator, with an electronic control unit that controls a mechanical actuator depending on the oil temperature.
Erfindungsgemäß ist die Sensoreinrichtung ausgeführt, als den ersten Parameter die Zulauftemperatur des Öls und insbesondere deren zeitlichen Verlauf zu messen, beispielsweise mittels eines Temperatursensors in der Zulaufleitung zum Ölthermostat. Die Zulauftemperatur ist ein Maß für die Öltemperatur, die am Eingang des Ölthermostats anliegt und in Abhängigkeit derer das Ölthermostat im Sollbetrieb eine vordefinierte Öffnungs- bzw. Schließstellung in Bezug auf die Ausgänge zu dem ersten und zweiten Strömungszweig annimmt. Besonders vorteilhaft ist, die Ölsumpftemperatur als die Zulauftemperatur zu messen, da in der Regel bereits ein Temperatursensor im Ölsumpf des Ölkreislaufs vorhanden ist, der genutzt werden kann. Die Ölsumpftemperatur kann beispielsweise mittels eines Ölsumpftemperatursensors gemessen werden, der in den bereits vorhandenen Ölstandssensor des Ölsumpfes integriert ist. Die Ölsumpftemperatur entspricht im Wesentlichen der am Eingang des Ölthermostats herrschenden Öltemperatur. Da sich die Öltemperatur des über eine Zulaufleitung vom Ölsumpf zum Ölthermostat beförderten Öls im Wesentlichen nicht verändert, kann die Zulauftemperatur auch an einer beliebigen anderen Stelle entlang der Zulaufleitung mittels eines entsprechend angeordneten Temperatursensors ermittelt werden.According to the invention, the sensor device is designed to measure the inlet temperature of the oil and in particular its progress over time as the first parameter, for example by means of a temperature sensor in the inlet line to the oil thermostat. The inlet temperature is a measure of the oil temperature which is present at the inlet of the oil thermostat and depending on which the oil thermostat assumes a predefined open or closed position with respect to the outlets to the first and second flow branch in target operation. It is particularly advantageous to measure the oil sump temperature as the inlet temperature, since there is usually already a temperature sensor in the oil sump of the oil circuit that can be used. The oil sump temperature can be measured, for example, by means of an oil sump temperature sensor that is integrated into the already existing oil level sensor of the oil sump. The oil sump temperature essentially corresponds to the oil temperature at the inlet of the oil thermostat. Since the oil temperature of the oil conveyed via an inlet line from the oil sump to the oil thermostat essentially does not change, the inlet temperature can also be determined at any other point along the inlet line using an appropriately arranged temperature sensor.
Die Sensoreinrichtung, die als den ersten Parameter die Zulauftemperatur misst, ist ferner ausgeführt, eine zweite Öltemperatur stromab des Ölkühlers und stromauf der Brennkraftmaschine zu messen und als den zweiten Parameter eine Temperaturdifferenz ΔT aus der Zulauftemperatur minus der zweiten Öltemperatur zu bestimmen.The sensor device, which measures the inlet temperature as the first parameter, is also designed to measure a second oil temperature downstream of the oil cooler and upstream of the internal combustion engine and to determine a temperature difference ΔT from the inlet temperature minus the second oil temperature as the second parameter.
Zur Messung der zweiten Öltemperatur kann ein Temperatursensor vorgesehen sein, der im ersten Strömungszweig stromab des Ölkühlers und stromauf einer Zusam menführung des ersten Strömungszweigs und des Bypass-Strömungszweigs angeordnet ist. Der Temperatursensor kann jedoch auch stromab eines von der Brennkraftmaschine angeordneten Ölfilters angeordnet sein. Vorzugweise ist der Temperatursensor als kombinierter Druck- und Temperatursensor ausgeführt, die in einer baulichen Einheit bereitgestellt werden. Eine weitere vorteilhafte Möglichkeit ist, den Temperatursensor in einen Ölfilterkopf zu integrieren.To measure the second oil temperature, a temperature sensor can be provided in the first flow branch downstream of the oil cooler and upstream of a combination menführung of the first flow branch and the bypass flow branch is arranged. However, the temperature sensor can also be arranged downstream of an oil filter arranged by the internal combustion engine. The temperature sensor is preferably designed as a combined pressure and temperature sensor, which is provided in one structural unit. Another advantageous option is to integrate the temperature sensor into an oil filter head.
Erfindungsgemäß ist die Auswerteeinrichtung gemäß diesen Varianten ausgeführt, das Auftreten einer Fehlfunktion des Ölthermostats anhand zumindest einer der drei folgenden Bedingungen (a) bis (c) zu erkennen:
- (a) Eine Fehlfunktion des Ölthermostats wird erkannt, wenn die Zulauftemperatur unterhalb des ersten Temperaturschwellenwerts liegt, mindestens eine vorgegebene Reaktionszeit vergangen ist, seit die Zulauftemperatur unterhalb des ersten Temperaturschwellenwerts liegt, und die Temperaturdifferenz ΔT aus der Zulauftemperatur minus der zweiten Öltemperatur größer als ein erster Schwellenwert ist.
- (a) A malfunction of the oil thermostat is detected if the inlet temperature is below the first temperature threshold, at least a predetermined response time has elapsed since the inlet temperature is below the first temperature threshold, and the temperature difference ΔT from the inlet temperature minus the second oil temperature is greater than a first threshold is.
Mit anderen Worten müsste der erste Ausgang des Ölthermostats zum Kühler in diesem Fall aufgrund der niedrigen Zulauftemperatur gemäß Soll-Betrieb eigentlich verschlossen sein. Wenn jedoch die Temperaturdifferenz ΔT größer als ein erster Schwellenwert ist, kann daraus geschlossen werden, dass eine Ölkühlung erfolgt und das Öl daher durch den Strömungszweig mit dem Kühler geflossen sein muss und somit eine Fehlfunktion des Thermostats vorliegt.In other words, the first outlet of the oil thermostat to the cooler should actually be closed in this case due to the low inlet temperature according to target operation. However, if the temperature difference ΔT is greater than a first threshold value, it can be concluded that oil cooling is taking place and the oil must therefore have flowed through the flow branch with the cooler, and the thermostat must therefore be malfunctioning.
Dieser erste Schwellenwert wird in Abhängigkeit von der durch den Ölkühler erzeugten Verringerung der Öltemperatur (Kühlleistung des Ölkühlers) festgelegt. Der erste Schwellenwert sollte beispielsweise größer sein als übliche, nicht von dem Ölkühler verursachte Schwankungen der Öltemperatur im Bereich zwischen Ölsumpf und Brennkraftmaschine, aber etwas kleiner als die durchschnittliche Kühlleistung des Ölkühlers. Die vorgegebene Reaktionszeit berücksichtigt ein zeitverzögerndes Verhalten des Ölthermostats und stellt eine Zeit dar, bis sich nach einer Änderung der Schaltstellung des Ölthermostats die dadurch resultierende Temperaturdifferenz ΔT stromab des Ölthermostats eingestellt haben müsste. Die Reaktionszeit hängt von der Bauart des Ölthermostats und von der Lage der Messstelle für die zweite Temperatur ab und kann z. B. experimentell festgelegt werden.This first threshold is set as a function of the drop in oil temperature (cooling capacity of the oil cooler) generated by the oil cooler. The first threshold value should, for example, be greater than usual fluctuations in the oil temperature in the area between the oil sump and the internal combustion engine that are not caused by the oil cooler, but somewhat smaller than the average cooling capacity of the oil cooler. The specified reaction time takes into account a time-delayed behavior of the oil thermostat and represents a time until the resulting temperature difference ΔT downstream of the oil thermostat should have set itself after a change in the switching position of the oil thermostat. The response time depends on the design of the oil thermostat and the position of the measuring point for the second temperature and can e.g. B. be determined experimentally.
(b) Das Auftreten einer Fehlfunktion des Ölthermostats kann ferner dann erkannt werden, wenn die Zulauftemperatur oberhalb des ersten Temperaturschwellenwerts liegt, mindestens die vorgegebene Reaktionszeit vergangen ist, seit die Zulauftemperatur oberhalb des ersten Temperaturschwellenwerts liegt, und die Temperaturdifferenz ΔT kleiner als ein zweiter Schwellenwert ist. Mit anderen Worten müsste bei einer Zulauftemperatur oberhalb des ersten Temperaturschwellenwerts der dem Ölthermostat zugeführte Ölstrom danach dem Ölkühler zugeleitet werden. Ist dies nicht der Fall, kann dies wiederum anhand der Temperaturdifferenz festgestellt werden, die kleiner ist als bei einer Kühlung des Öls durch den Ölkühler. Der zweite Schwellenwert kann beispielsweise etwas unterhalb der durch den Kühler normalerweise bewirkten Differenztemperatur ΔT festgelegt werden.(b) The occurrence of a malfunction of the oil thermostat can also be detected when the inlet temperature is above the first temperature threshold, at least the specified response time has passed since the inlet temperature is above the first temperature threshold, and the temperature difference ΔT is less than a second threshold . In other words, if the inlet temperature is above the first temperature threshold value, the oil flow fed to the oil thermostat would then have to be fed to the oil cooler. If this is not the case, this can again be determined using the temperature difference, which is smaller than when the oil is cooled by the oil cooler. The second threshold value can, for example, be set slightly below the differential temperature ΔT normally caused by the cooler.
(c) Das Auftreten einer Fehlfunktion des Ölthermostats kann ferner dann erkannt werden, wenn nach einer Überschreitung des ersten Temperaturschwellenwerts durch die Zulauftemperatur ein Gradient, insbesondere ein Anstieg der Temperaturdifferenz ΔT, langsamer verläuft als ein vorgegebener Soll-Anstieg der Temperaturdifferenz. Die Auswerteeinrichtung wertet somit den Verlauf der Differenztemperatur über die Zeit aus und kann diesen mit einem hinterlegten Soll-Anstieg der Temperaturdifferenz vergleichen. Ein besonderer Vorzug dieser Variante liegt darin, dass die Auswertung des Anstiegs der Temperaturdifferenz als Frühindikator für eine beginnende Fehlfunktion des Ölthermostats herangezogen werden kann. Untersuchungen im Rahmen der Erfindung haben gezeigt, dass vor einer vollständigen Fehlfunktion des Ölthermostats dessen Stellglied ein beginnendes Klemmen oder Hakeln zeigt, so dass dieses nicht schrittweise aufmacht, sondern sich relativ spät bewegt. Dies kann anhand eines verzögerten Anstiegs der Differenztemperatur erkannt werden.(c) The occurrence of a malfunction of the oil thermostat can also be detected if, after the inlet temperature has exceeded the first temperature threshold value, a gradient, in particular an increase in the temperature difference ΔT, is slower than a specified setpoint increase in the temperature difference. The evaluation device thus evaluates the course of the differential temperature over time and can compare this with a stored target increase in the temperature differential. A particular advantage of this variant is that the evaluation of the increase in the temperature difference can be used as an early indicator of an incipient malfunction of the oil thermostat. Investigations within the scope of the invention have shown that before a complete malfunction of the oil thermostat, its actuator shows the beginning of jamming or hooking, so that it does not open gradually, but moves relatively late. This can be recognized by a delayed increase in the differential temperature.
Zur weiteren Verbesserung der Genauigkeit der Erkennung einer Fehlfunktion können die vorgenannten Schwellenwerte motordrehzahlabhängig gewählt werden, derart, dass bei größerer aktueller Motordrehzahl größere Schwellenwerte eingestellt werden. Dies berücksichtigt die Tatsache, dass mit zunehmender Motordrehzahl die Kühlleistung des Ölkühlers zunimmt und somit der erwartete Wert der Temperaturdifferenz.In order to further improve the accuracy of the detection of a malfunction, the aforementioned threshold values can be selected as a function of the engine speed, such that larger threshold values are set at a higher current engine speed. This takes into account the fact that as the engine speed increases, the cooling capacity of the oil cooler increases and thus the expected value of the temperature difference.
Im Rahmen der Erfindung besteht weiterhin die Möglichkeit, dass die Sensoreinrichtung ausgeführt ist, als den zweiten Parameter einen Öldruckverlauf, insbesondere einen zeitlichen Verlauf des Öldrucks, mittels eines Drucksensors an einer Druckmessstelle zu messen, die stromab des ersten Ausgangs des Ölthermostats und stromauf zur Brennkraftmaschine angeordnet ist. Gemäß dieser Variante ist die Auswerteeinrichtung ausgeführt, eine Fehlfunktion des Ölthermostats zu erkennen, wenn der gemessene zeitliche Verlauf des Öldrucks in einem Bereich der Zulauftemperatur, der zwischen dem ersten Öltemperaturschwellenwert und dem vorgenannten zweiten Temperaturschwellenwert liegt, keinen Druckausschlag in Form eines negativen oder positiven Peaks zeigt. Ein solcher Druckausschlag entspricht einer Peak-förmigen Druckänderung, deren Peakhöhe größer als ein vorbestimmter Wert ist. Dies beruht auf der Erkenntnis, dass der Strömungswiderstand in dem Temperaturbereich, in dem der erste Strömungszweig mit Ölkühler bereits geöffnet ist und der Bypass-Strömungszweig noch nicht vollständig geschlossen ist, minimal ist und so der Druckverlauf in diesem Temperaturbereich einen Peak aufweisen müsste, wenn das Ölthermostat fehlerfrei funktioniert. Fehlt dieser Druckpeak, kann hieraus eine Fehlfunktion des Ölthermostats abgeleitet werden. Dieser vorbestimmte Wert zum Erkennen eines Druckausschlags kann ölkreisspezifisch experimentell festgelegt werden, derart, dass Druckausschläge, die diesen Wert überschreiten, nicht von normalen Druckschwankungen, sondern aus einem geänderten Strömungswiderstands stromab des Ölthermostats korrespondierend zu zumindest teilweise geöffnetem ersten und zweiten Strömungszweig resultieren.Within the scope of the invention, there is also the possibility that the sensor device is designed such that the second parameter is an oil pressure profile, in particular a time profile of the oil pressure, by means of a pressure sensor at a pressure measuring point to be measured, which is arranged downstream of the first output of the oil thermostat and upstream of the internal combustion engine. According to this variant, the evaluation device is designed to detect a malfunction of the oil thermostat if the measured time profile of the oil pressure shows no pressure deflection in the form of a negative or positive peak in a range of the inlet temperature that lies between the first oil temperature threshold value and the aforementioned second temperature threshold value . Such a pressure deflection corresponds to a peak-shaped pressure change whose peak height is greater than a predetermined value. This is based on the finding that the flow resistance in the temperature range in which the first flow branch with the oil cooler is already open and the bypass flow branch is not yet completely closed is minimal and the pressure profile in this temperature range should therefore have a peak if the Oil thermostat works properly. If this pressure peak is missing, a malfunction of the oil thermostat can be deduced. This predetermined value for detecting a pressure ripple can be experimentally determined oil circuit-specifically, such that pressure ripples that exceed this value do not result from normal pressure fluctuations, but from a changed flow resistance downstream of the oil thermostat corresponding to the at least partially open first and second flow branch.
Eine besonders vorteilhafte Variante dieser Ausgestaltungsform sieht hierbei vor, dass die Druckmessstelle bzw. der Drucksensor zur Messung des zeitlichen Verlaufs des Öldrucks im ersten Strömungszweig zwischen dem ersten Ausgang des Ölthermostats und dem Ölkühler angeordnet ist und dass der Druckausschlag ein negativer Peak ist.A particularly advantageous variant of this embodiment provides that the pressure measuring point or the pressure sensor for measuring the time profile of the oil pressure is arranged in the first flow branch between the first outlet of the oil thermostat and the oil cooler and that the pressure deflection is a negative peak.
Es besteht jedoch auch die Möglichkeit, die Druckmessstelle stromab des Ölkühlers und nach einer Zusammenführung des ersten Strömungszweigs und des Bypass-Strömungszweigs anzuordnen. In diesem Fall ist der erwartete Druckausschlag im Soll-Betrieb ein positiver Peak und die Peakhöhe.However, there is also the possibility of arranging the pressure measuring point downstream of the oil cooler and after the first flow branch and the bypass flow branch have been combined. In this case, the expected pressure deflection in target operation is a positive peak and the peak height.
Vorstehend wurde bereits erwähnt, dass als den ersten Parameter die Zulauftemperatur des Öls gemessen werden kann, wobei vorzugsweise als Zulauftemperatur die Ölsumpftemperatur gemessen wird. Aus der aktuellen Zulauftemperatur kann der Soll-Betriebszustand des Ölthermostats unmittelbar abgeleitet werden, da das Stellglied des Ölthermostats die vorgegebenen Stellpositionen in Abhängigkeit von der Zulauftemperatur einnimmt.It was already mentioned above that the inlet temperature of the oil can be measured as the first parameter, with the oil sump temperature preferably being measured as the inlet temperature. The target operating status of the oil thermostat can be derived directly from the current inlet temperature, since the actuator of the oil thermostat assumes the specified setting positions depending on the inlet temperature.
Im Rahmen der Erfindung besteht jedoch auch die Möglichkeit, andere Kenngrößen für den ersten Parameter zu verwenden, aus bzw. mit denen ebenfalls der Soll-Betrieb des Ölthermostats ableitbar ist, um so bereits im Fahrzeug vorhandene bzw. bereitgestellte Größen zu nutzen. Beispielsweise kann die Kühlwassertemperatur verwendet werden, da die Verläufe der Öltemperatur und der Kühlwassertemperatur im Soll-Betrieb miteinander korreliert sind. Aus der Kühlwassertemperatur kann somit ein Verlauf der Öltemperatur in der Zulaufleitung abgeleitet werden, aus der wiederum der Soll-Betrieb des Ölthermostats ableitbar ist.Within the scope of the invention, however, there is also the possibility of using other parameters for the first parameter, from or with which the target operation of the oil thermostat can also be derived, in order to use variables already present or provided in the vehicle. For example, the cooling water temperature can be used since the curves of the oil temperature and the cooling water temperature are correlated with one another in target operation. A profile of the oil temperature in the supply line can thus be derived from the cooling water temperature, from which in turn the target operation of the oil thermostat can be derived.
Ferner können definierte Betriebszustände des Fahrzeugs verwendet werden. Ein Beispiel hierfür ist der Betriebszustand, wenn das Fahrzeug einen Kaltstart durchführt, oder bei einer Fahrt unter Volllast. Bei einem Kaltstart ist die Ölzulauftemperatur unterhalb des ersten Temperaturschwellenwerts, so dass der erste Strömungszweig zum Ölkühler im Normalbetrieb geschlossen sein müsste. Umgekehrt ist bei Fahrt unter Volllast dieser Strömungszweig in der Regel geöffnet, falls kein Defekt vorliegt.Furthermore, defined operating states of the vehicle can be used. An example of this is the operating state when the vehicle performs a cold start or when driving under full load. In the case of a cold start, the oil inlet temperature is below the first temperature threshold value, so that the first flow branch to the oil cooler would have to be closed during normal operation. Conversely, when driving under full load, this flow branch is usually open if there is no defect.
In Kombination mit den vorstehend genannten verschiedenen Möglichkeiten, wenigstens einen ersten Parameter zu bestimmen, mittels dessen ein aktueller Soll-Betrieb des Ölthermostats ableitbar ist, bestehen im Rahmen der Erfindung die nachfolgenden weiteren Ausführungsvarianten, wenigstens einen zweiten Parameter zu bestimmen, mittels dessen ein aktueller Ist-Betrieb des Ölthermostats ableitbar ist.In combination with the above-mentioned various options for determining at least one first parameter, by means of which a current setpoint operation of the oil thermostat can be derived, the following further embodiment variants exist within the scope of the invention for determining at least one second parameter, by means of which a current actual value can be determined -Operation of the oil thermostat can be derived.
Eine weitere Möglichkeit der erfindungsgemäßen Realisierung sieht beispielsweise vor, einen Gradient einer Zulauftemperatur des Öls als den zweiten Parameter zu bestimmen. Vorzugsweise wird hierzu ein Gradient der Ölsumpftemperatur bestimmt. Gemäß dieser Variante ist die Auswerteeinrichtung ausgeführt, in Abhängigkeit von dem bestimmten Wert des ersten Parameters eine vorbestimmte und im Speicher der Auswerteeinrichtung hinterlegte Soll-Kennlinie des Gradienten der Zulauftemperatur zu ermitteln und eine Fehlfunktion des Ölthermostats zu erkennen, wenn der gemessene Gradient der Zulauftemperatur nicht innerhalb vorgegebener Grenzen mit der Soll-Kennlinie übereinstimmt.A further possibility of the implementation according to the invention provides, for example, for a gradient of an inlet temperature of the oil to be determined as the second parameter. A gradient of the oil sump temperature is preferably determined for this purpose. According to this variant, the evaluation device is designed to determine a predetermined setpoint characteristic curve of the gradient of the inlet temperature that is stored in the memory of the evaluation device as a function of the determined value of the first parameter and to detect a malfunction of the oil thermostat if the measured gradient of the inlet temperature is not within specified limits agrees with the target characteristic.
Nachfolgend wird ein Beispiel erläutert, bei dem als erster Parameter ein Betriebszustand des Fahrzeugs bestimmt wird. Fährt das Fahrzeug beispielsweise bei Volllast eine Steigung hinauf, resultiert daraus ein bekannter Temperaturanstieg im Ölsumpf, der vorab experimentell bestimmt und in Form einer Kennlinie in der Auswerteeinrichtung hinterlegt wurde. Erkennt die Auswerteeinrichtung anhand des bestimmten Betriebszustands eine Fahrt unter Volllast, vergleicht die Auswerteeinrichtung den gemessenen Temperaturanstieg der Zulauftemperatur mit der zuvor hinterlegten Kennlinie für Fahrten unter Volllast. Weicht der anhand des zweiten Parameters bestimmte aktuelle Temperaturanstieg der Ölzulauftemperatur von dem zuvor hinterlegten Temperaturanstieg gemäß Kennlinie ab, kann daraus wiederum eine Fehlfunktion des Ölthermostats abgeleitet werden.An example is explained below in which an operating state of the vehicle is determined as the first parameter. For example, if the vehicle drives up an incline at full load, this results in a known increase in temperature in the oil sump, which was previously determined experimentally and stored in the evaluation device in the form of a characteristic curve. If the evaluation device recognizes driving under full load on the basis of the specific operating state, the evaluation device compares the measured rise in temperature of the inlet temperature with the previously stored characteristic curve for driving under full load. If the current temperature increase in the oil inlet temperature determined using the second parameter deviates from the previously stored temperature increase according to the characteristic curve, a malfunction of the oil thermostat can in turn be derived from this.
Im Rahmen der Erfindung besteht ferner die Möglichkeit, dass die Sensoreinrichtung ausgeführt ist, als den zweiten Parameter eine Stellung und/oder eine Bewegung eines Stellglieds des Ölthermostats zu erfassen. In diesem Fall ist die Auswerteeinrichtung ausgebildet, die Fehlfunktion des Ölthermostats anhand der erfassten Stellung und/oder Bewegung des Stellglieds zu erkennen, indem die erfasste Stellung und/oder Bewegung des Stellglieds mit der erwarteten Stellung und/oder Bewegung gemäß des in Abhängigkeit von dem ersten Parameter bestimmten Soll-Betriebs verglichen wird. Beispielsweise kann die Fehlfunktion des Ölthermostats bekannt werden, wenn in einem vorgegebenen Öltemperaturbereich oder Kühlwassertemperaturbereich, in dem sich das Stellglied bewegen müsste, keine Bewegung des Stellglieds erfasst wird. Ferner kann die Fehlfunktion des Ölthermostats erkannt werden, wenn bei einem Kaltstart das Stellglied in einer Stellung ist, in der der erste Ausgang geöffnet ist und/oder wenn bei einem Fahrbetrieb unter Volllast das Stellglied in einer Stellung ist, in der der erste Ausgang geschlossen ist.Within the scope of the invention, there is also the possibility that the sensor device is designed to detect a position and/or a movement of an actuator of the oil thermostat as the second parameter. In this case, the evaluation device is designed to detect the malfunction of the oil thermostat based on the detected position and/or movement of the actuator by comparing the detected position and/or movement of the actuator with the expected position and/or movement according to the depending on the first Parameter specific target operation is compared. For example, the malfunction of the oil thermostat can become known if no movement of the actuator is detected in a predetermined oil temperature range or cooling water temperature range in which the actuator would have to move. Furthermore, the malfunction of the oil thermostat can be detected when, during a cold start, the actuator is in a position in which the first output is open and/or when the actuator is in a position in which the first output is closed when driving under full load .
Zur Erkennung einer Stellung und/oder Bewegung des Stellglieds kann ein Wegsensor vorgesehen sein, der mechanisch mit dem Stellglied bewegungsgekoppelt ist. Beispielsweise kann der Wegsensor eine Koppelstange aufweisen, die mit dem Stellglied des Ölthermostats bewegungsgekoppelt ist.To detect a position and/or movement of the actuator, a displacement sensor can be provided, which is mechanically coupled in terms of movement to the actuator. For example, the displacement sensor can have a coupling rod which is coupled in terms of movement to the actuator of the oil thermostat.
Eine alternative Variante sieht hierbei vor, dass die Sensoreinrichtung als elektrischer Schwingkreis mit einer Spule ausgeführt ist, wobei die Spule von außen am oder in der Nähe des Ölthermostats angeordnet ist, derart, dass eine Bewegung des Stellglieds des Ölthermostats die Induktivität der Spule und damit eine Schwingungsfrequenz des Schwingkreises verändert.An alternative variant provides that the sensor device is designed as an electrical oscillating circuit with a coil, with the coil being arranged from the outside on or near the oil thermostat in such a way that a movement of the Actuator of the oil thermostat changes the inductance of the coil and thus an oscillation frequency of the oscillating circuit.
Gemäß einer weiteren Variante kann die Sensoreinrichtung eine Sendespule und eine Empfängerspule aufweisen, die jeweils auf gegenüberliegenden Seiten von außen am oder in der Nähe des Ölthermostats angeordnet sind, so dass eine Bewegung des Stellglieds des Ölthermostats ein von der Senderspule in der Empfängerspule induziertes Signal verändert.According to a further variant, the sensor device can have a transmitter coil and a receiver coil, which are each arranged on opposite sides from the outside on or in the vicinity of the oil thermostat, so that a movement of the actuator of the oil thermostat changes a signal induced by the transmitter coil in the receiver coil.
Der Vorteil der beiden letzteren Varianten gegenüber einer mechanischen Kopplung mit dem Stellglied ist, dass kein Kontakt zum thermostatisch geregelten Medium (Öl) vorhanden ist und keine zusätzlichen Abdichtungselemente, wie sie im Falle einer Koppelstange notwendig wären, benötigt werden. An weiterer Vorteil ist, dass das überwachende Systemelement in Form der Sensoreinrichtung mit der mindestens einen Spule eine wesentlich höhere durchschnittliche Lebensdauer als das zu überwachende Element (Ölthermostat) aufweist und somit das Ölthermostat für die Gesamtlebensdauer des Fahrzeuges überwachen kann.The advantage of the latter two variants compared to a mechanical coupling with the actuator is that there is no contact with the thermostatically controlled medium (oil) and no additional sealing elements are required, as would be necessary in the case of a coupling rod. Another advantage is that the monitoring system element in the form of the sensor device with at least one coil has a significantly longer average service life than the element to be monitored (oil thermostat) and can therefore monitor the oil thermostat for the entire service life of the vehicle.
Eine vorteilhafte Variante der vorgenannten Sensoreinrichtungen mit Schwingkreis oder Sende- und Empfängerspule sieht vor, dass die Vorrichtung als mobile Prüfvorrichtung für den Werkstatteinsatz ausgeführt ist. Die mobile Prüfvorrichtung umfasst ferner Befestigungsmittel, um die Sensorvorrichtung außen am oder in der Nähe des Ölthermostats temporär für einen Messvorgang anzuordnen. Damit können auch Ölthermostate von Fahrzeugen, die nicht ab Werk mit einer Überwachungsvorrichtung für das Ölthermostat ausgestattet sind, nachträglich mit geringem Wartungsaufwand überprüft werden.An advantageous variant of the aforementioned sensor devices with an oscillating circuit or transmitter and receiver coil provides that the device is designed as a mobile test device for workshop use. The mobile test device also includes fastening means in order to temporarily arrange the sensor device outside on or in the vicinity of the oil thermostat for a measurement process. This means that the oil thermostats of vehicles that are not factory-equipped with a monitoring device for the oil thermostat can be checked later with little maintenance.
Im Rahmen der Erfindung besteht ferner die Möglichkeit, die Sensoreinrichtung als einen in das Ölthermostat integrierten Schaltkreis auszubilden, der ausgeführt ist, eine Stellung und/oder Bewegung des Stellglieds des Ölthermostats mittels integrierter Schaltkontakte zu erfassen. Beispielsweise kann der Schaltkreis so ausgeführt sein, dass er die Endlagen des Ventiltellers des Ölthermostats mittels entsprechender Schaltkontakte überwacht. Der integrierte Schaltkreis ist ferner so ausgeführt, dass er seine Versorgungsenergie mittels eines Energie-Harvesting-Schaltkreises der Ölwärme entzieht und ein Messsignal drahtlos, vorzugsweise mittels einer Nahfeldfunkübertragung, an die Auswerteeinrichtung übermittelt. Ein Vorteil dieser Variante ist wiederum, dass keine zusätzlichen Abdichtungselemente zur Anbringung der Sensorvorrichtung vorgesehen sein müssen, da der integrierte Schaltkreis im Innern des Ölthermostats vorgesehen ist, ohne eine mechanische Verbindung nach außen aufzuweisen.Within the scope of the invention, there is also the possibility of designing the sensor device as a circuit integrated into the oil thermostat, which is designed to detect a position and/or movement of the actuator of the oil thermostat by means of integrated switching contacts. For example, the circuit can be designed in such a way that it monitors the end positions of the valve plate of the oil thermostat using appropriate switch contacts. The integrated circuit is also designed in such a way that it draws its supply energy from the oil heat by means of an energy harvesting circuit and transmits a measurement signal wirelessly, preferably by means of near-field radio transmission, to the evaluation device. A benefit of this Another variant is that no additional sealing elements have to be provided for attaching the sensor device, since the integrated circuit is provided inside the oil thermostat without having a mechanical connection to the outside.
Eine weitere Möglichkeit zur Ausgestaltung der Sensoreinrichtung sieht vor, einen Temperatursensor an einer Messstelle anzuordnen, die im ersten Strömungszweig zwischen dem Ölthermostat und dem Ölkühler angeordnet ist. Die hiermit gemessene Öltemperatur stromab des ersten Ausgangs des Ölthermostats und noch vor dem Ölkühler kann einerseits als der erste Parameter der Sensoreinrichtung bestimmt werden, da die Temperatur annäherungsweise mit der Zulauftemperatur übereinstimmt. Aus der gemessenen Temperatur kann somit der Soll-Betrieb des Ölthermostats abgeleitet werden.A further possibility for designing the sensor device provides for arranging a temperature sensor at a measuring point which is arranged in the first flow branch between the oil thermostat and the oil cooler. The oil temperature measured in this way downstream of the first output of the oil thermostat and before the oil cooler can be determined as the first parameter of the sensor device, since the temperature approximately corresponds to the inlet temperature. The target operation of the oil thermostat can thus be derived from the measured temperature.
Wird der erste Parameter jedoch anhand einer der anderen zuvor genannten Alternativen bestimmt, kann die Temperaturmessung unmittelbar nach dem ersten Ausgang des Ölthermostats auch zur Bestimmung des zweiten Parameters verwendet werden. Eine Fehlfunktion des Ölthermostats kann durch die Auswerteeinrichtung beispielsweise dann erkannt werden, wenn die gemessene Öltemperatur an dieser Stelle im Wesentlichen unverändert bleibt, nachdem gemäß der bestimmten ersten Größe eine Öffnung oder Schließung des ersten Ausgangs erfolgt sein müsste.However, if the first parameter is determined using one of the other alternatives mentioned above, the temperature measurement immediately after the first output of the oil thermostat can also be used to determine the second parameter. A malfunction of the oil thermostat can be detected by the evaluation device, for example, if the measured oil temperature remains essentially unchanged at this point after the first output should have opened or closed according to the determined first variable.
Mit der vorliegenden Erfindung können auch zwei oder mehrere Thermostate in Parallelschaltung überwacht werden, beispielsweise ein kleines und ein großes Thermostat, die entweder gleiche oder aber auch unterschiedliche Temperatureinstellungen aufweisen und bei denen der Abfluss des Öles unterschiedliche Druckölverbraucher versorgt.The present invention can also be used to monitor two or more thermostats connected in parallel, for example a small and a large thermostat, which have either the same or different temperature settings and in which the oil discharge supplies different pressure oil consumers.
Ein weiterer Aspekt der Erfindung betrifft ein Fahrzeug, insbesondere ein Nutzfahrzeug, mit einer Vorrichtung wie hierin offenbart. Die zuvor beschriebenen bevorzugten Ausführungsformen, Varianten und Merkmale der Erfindung sind beliebig miteinander kombinierbar. Weitere Einzelheiten und Vorteile der Erfindung werden im Folgenden unter Bezug auf die beigefügten Zeichnungen beschrieben. Es zeigen:
Figur 1- eine schematische Darstellung eines Ölkreislaufs einer Brennkraftmaschine zur Illustration verschiedener Ausführungsformen;
Figur 2- einen charakteristischen Temperaturverlauf bei einer Fehlfunktion des Ölthermostats;
- Figur 3
- einen charakteristischen Temperaturverlauf bei einer Fehlfunktion des Ölthermostats;
- Figur 4
- einen Temperaturanstieg bei funktionierendem und bei defektem Ölthermostat;
- Figur 5
- einen öltemperaturabhängigen Verlauf des Öldrucks;
Figur 6- Ausführungsvarianten zur Bestimmung der Stellung und/oder Bewegung des Stellglieds des Ölthermostats; und
- Figur 7
- weitere Ausführungsvarianten zur Bestimmung der Stellung und/oder Bewegung des Stellglieds des Ölthermostats.
- figure 1
- a schematic representation of an oil circuit of an internal combustion engine to illustrate various embodiments;
- figure 2
- a characteristic course of temperature in the event of a malfunction of the oil thermostat;
- figure 3
- a characteristic course of temperature in the event of a malfunction of the oil thermostat;
- figure 4
- an increase in temperature with working and with defective oil thermostat;
- figure 5
- an oil temperature-dependent profile of the oil pressure;
- figure 6
- Design variants for determining the position and/or movement of the actuator of the oil thermostat; and
- figure 7
- further design variants for determining the position and/or movement of the actuator of the oil thermostat.
In dem Ölkreislauf 1 ist eine Ölwanne 2 angeordnet, in der der Ölsumpf 2a angeordnet ist, dessen Füllstand mit einer Ölstandssonde 3 überwacht wird. Das Öl aus dem Ölsumpf 2a wird über eine Zulaufleitung 5 dem Durchfluss-Eingang 11 eines Ölthermostats 10 zugeführt. In der Zulaufleitung 5 sind eine Ölpumpe 6, ein Überdruckventil 7 sowie ein Rücklauf-Sperrventil 8 angeordnet.In the
Das Ölthermostat 10 ist beispielsweise als Ringschieberölthermostat oder Wachsausdehnungsölthermostat ausgebildet und enthält ein Stellglied, das sich in Abhängigkeit von der am Eingang 11 des Ölthermostats 10 anliegenden Öltemperatur (Zulauftemperatur T2) in eine bestimmte Stellung bewegt. Über die Leitung 9 liegt das dem Ölthermostat zugeführte Öl an einem Steuereingang des Ölthermostatventils 10 an und führt beispielsweise im Falle eines Wachsausdehnungsthermostats in Abhängigkeit von der Öltemperatur zu einer Erwärmung und damit Ausdehnung oder zu einer Abkühlung und ein In-sich-Zusammenziehen des Stellglieds des Ölthermostats, so dass die Ventilteller des Stellglieds bewegt werden, um einen ersten Ausgang 12 des Ölthermostats 10 zu öffnen bzw. zu schließen und den zweiten Ausgang 13 des Ölthermostats 10 zu schließen bzw. zu öffnen.The
Ist die Zulauftemperatur T2 des Öls kleiner als ein erster Temperaturschwellenwert T1, ist derjenige Ausgang 12 des Ölthermostats 10 verschlossen, der die Zulaufleitung 5 mit einem ersten Strömungszweig 17 verbindet, in dem ein Ölkühler 16 angeordnet ist. Stattdessen wird das Öl über den zweiten Ausgang 13 des Ölthermostats 10 einem zweiten Bypass-Strömungszweig 18 zugeführt, der den Ölkühler 16 umgeht. Ist die Zulauftemperatur T2 dagegen größer als ein zweiter Temperaturschwellenwert T1*, der über dem Wert T1 liegt, ist der zweite Ausgang 13 vollständig geschlossen und der erste Ausgang 12 geöffnet, so dass das Öl ausschließlich über den Ölkühler 16 strömt. Im Bereich zwischen T1 und T1* ist der erste Ausgang geöffnet und der zweite Ausgang nur teilweise verschlossen.If the inlet temperature T2 of the oil is lower than a first temperature threshold value T1, the
Der erste Strömungszweig 17 und der zweite Strömungszweig 18 werden nach dem Ölkühler 16 zu einem gemeinsamen Strömungsabschnitt 19 zusammengeführt. Das Öl durchströmt dann einen Ölfilter 20, der ferner ein Filterserviceventil 21 aufweist sowie ein Filterumgehungsventil 22. Stromab des Ölfilters 20 folgen ein Siphon 23 im Ölfilterkopf und ein in den Ölfilterkopf integrierter Öldrucksensor 25. Anschließend wird das Öl über den Leitungsabschnitt 26 der Brennkraftmaschine (nicht dargestellt) zugeführt.The
Die vorstehend beschriebenen Bestandteile des Ölkreislaufs 1 sind an sich aus dem Stand der Technik bekannt und müssen hier nicht weiter detailliert beschrieben werden.The components of the
Erfindungsgemäß ist ferner eine Vorrichtung zur Überwachung des Ölthermostats vorgesehen, um eine Fehlfunktion des Ölthermostats erkennen zu können. Die Vorrichtung umfasst eine Sensoreinrichtung, die ausgebildet ist, wenigstens einen ersten Parameter zu bestimmen, mittels dessen oder aus dem ein aktueller Betrieb des Ölthermostats 10 ableitbar ist.According to the invention, a device for monitoring the oil thermostat is also provided in order to be able to detect a malfunction of the oil thermostat. The device includes a sensor device that is designed to determine at least one first parameter, by means of which or from which a current operation of the
Die Sensoreinrichtung kann hierzu beispielsweise einen Temperatursensor 4 umfassen, der die Ölsumpftemperatur als ersten Parameter bestimmt. Die Ölsumpftemperatur T2 entspricht im Wesentlichen der Öltemperatur, die am Ölthermostat 10 anliegt und die im Sollbetrieb die Stellung des Stellglieds festlegt. Der Ölsumpftemperatursensor 4 kann in den Ölstandssensor 3 integriert sein und als sog. Kombi-Sensor bereitgestellt werden. Wie vorstehend bereits erwähnt, kann aus der bestimmten Ölsumpftemperatur direkt der Sollbetriebszustand des Ölthermostats 10 abgeleitet werden. Wie vorstehend bereits erläutert, ist der erste Ausgang 12 zum ersten Strömungszweig 17, aufweisend den Ölkühler 16, bei Ölsumpftemperaturen T2 < T1 geschlossen. Bei einer Temperatur T2 ≥ T1 und T2 ≤ T1* ist der Durchfluss durch den ersten Strömungszweig 17 offen, und der Bypass-Strömungszweig 18 ist ebenfalls noch teilweise offen. In einem Bereich der Ölsumpftemperatur T2 > T1* ist der Durchfluss durch den ersten Strömungszweig 17 voll geöffnet und der zweite Ausgang 13 und damit der Bypass-Strömungszweig 18 vollständig geschlossen. Beispielhafte Werte für T1 liegen im Bereich von 95 Grad bis 105 Grad und für T1* bei ca. 120 Grad.For this purpose, the sensor device can comprise a temperature sensor 4, for example, which determines the oil sump temperature as the first parameter. The oil sump temperature T2 essentially corresponds to the oil temperature which is present at the
Die Sensoreinrichtung der Vorrichtung zur Überwachung des Ölthermostats ist ferner ausgebildet, einen zweiten Parameter zu bestimmen, mittels derer ein aktueller Ist-Betrieb des Ölthermostats ableitbar ist. Hierfür kann beispielsweise der Temperatursensor 14b verwendet werden, der stromab des Ölkühlers 16 im ersten Strömungszweig 17 angeordnet ist, bevor dieser mit dem Bypass-Strömungszweig 18 zusammengeführt wird. Mit diesem Temperatursensor 14b kann eine zweite Öltemperatur T3 stromab des Ölkühlers 16 gemessen werden. Aus dieser zweiten Öltemperatur T3 kann dann eine Temperaturdifferenz ΔT aus der Zulauftemperatur T2 minus der zweiten Öltemperatur T3 bestimmt werden, anhand derer festgestellt werden kann, ob der Ist-Betrieb des Ölthermostats 10 mit dem erwarteten Sollbetrieb übereinstimmt.The sensor device of the device for monitoring the oil thermostat is also designed to determine a second parameter, by means of which a current actual operation of the oil thermostat can be derived. For this purpose, for example, the
Dies ist beispielsweise in
In dem dargestellten Fall ist die Zulauftemperatur T2 kleiner als die Öffnungstemperatur T1 des ersten Ausgangs 12 des Ölthermostats 10. Im Sollbetrieb dürfte somit der erste Strömungszweig nicht von Öl durchströmt werden, da der erste Ausgang 12 in diesem Fall geschlossen sein müsste.
Eine über eine Signaleingangsleitung 41 mit der Sensoreinrichtung 4, 14b verbundene Auswerteeinheit 40 überprüft nun anhand der ermittelten Messwerte, ob die bestimmte Temperaturdifferenz ΔT einen Wert aufweist, der gemäß eines Sollbetriebs erwartet wird, oder ob eine Fehlfunktion des Ölthermostats 10 vorliegt. Die Auswerteeinheit 40 prüft, ob die Temperaturdifferenz ΔT aus der Zulauftemperatur T2 minus der zweiten Öltemperatur T3 kleiner als ein vorbestimmter erster Temperaturschwellenwert ΔT1 ist.An
Eine Fehlfunktion des Ölthermostats wird erkannt, wenn die Zulauftemperatur unterhalb des ersten Temperaturschwellenwerts liegt, mindestens eine vorgegebene Reaktionszeit Z1 vergangen ist, seit die Zulauftemperatur unterhalb des ersten Temperaturschwellenwerts T1 liegt, und die Temperaturdifferenz ΔT aus der Zulauftemperatur minus der zweiten Öltemperatur größer als ein erster Schwellenwert ΔT1 ist.A malfunction of the oil thermostat is detected when the inlet temperature is below the first temperature threshold, at least a predetermined response time Z1 has passed since the inlet temperature is below the first temperature threshold T1, and the temperature difference ΔT from the inlet temperature minus the second oil temperature is greater than a first threshold value ΔT1 is.
Wenn jedoch die Temperaturdifferenz ΔT größer als ein erster Schwellenwert ΔT1 ist, kann daraus geschlossen werden, dass eine Ölkühlung erfolgt und das Öl daher durch den Strömungszweig 17 mit dem Kühler 16 geflossen sein muss und somit eine Fehlfunktion des Thermostats 10 vorliegt.However, if the temperature difference ΔT is greater than a first threshold value ΔT1, it can be concluded that oil cooling is taking place and the oil must therefore have flowed through the
Der erste Schwellenwert ΔT1 wird in Abhängigkeit der durch den Ölkühler erzeugten Verringerung der Öltemperatur (Kühlleistung des Ölkühlers) festgelegt. Der erste Schwellenwert sollte beispielsweise größer sein als übliche, nicht von dem Ölkühler verursachte Schwankungen der Öltemperatur im Bereich zwischen Ölsumpf und Brennkraftmaschine, aber etwas kleiner als die durchschnittliche Kühlleistung des Ölkühlers. Die vorgegebene Reaktionszeit Z1 berücksichtigt ein zeitverzögerndes Verhalten des Ölthermostats und stellt eine Zeit dar, bis sich nach einer Änderung der Schaltstellung des Ölthermostats die dadurch resultierende Temperaturdifferenz ΔT stromab des Ölthermostats eingestellt haben müsste. Die Reaktionszeit hängt von der Bauart des Ölthermostats und von der Lage der Messstelle für die zweite Temperatur ab und kann z. B. experimentell festgelegt werden.The first threshold ΔT1 is set depending on the drop in oil temperature (cooling capacity of the oil cooler) generated by the oil cooler. The first threshold value should, for example, be greater than usual fluctuations in the oil temperature in the area between the oil sump and the internal combustion engine that are not caused by the oil cooler, but somewhat smaller than the average cooling capacity of the oil cooler. The specified response time Z1 takes into account a time-delayed behavior of the oil thermostat and represents a time after a change in the switching position of the oil thermostat, until the resulting temperature difference ΔT downstream of the oil thermostat should have set itself. The response time depends on the design of the oil thermostat and the position of the measuring point for the second temperature and can e.g. B. be determined experimentally.
Erkennt die Auswerteeinrichtung 40 eine Fehlfunktion des Ölthermostats 10, gibt sie über die Ausgangsleitung 42 ein Warnsignal aus, das z. B. über eine Anzeigevorrichtung im Cockpit des Fahrzeugs ausgeben wird.If the
In
Die gestrichelte Linie, die mit dem Bezugszeichen T3 gekennzeichnet ist, gibt den Verlauf der Öltemperatur an, die vor der Brennkraftmaschine, aber stromab des Ölkühlers 16 gemessen wird, beispielsweise mit dem Temperatursensor 24.The dashed line, which is identified by the reference character T3, indicates the course of the oil temperature, which is measured in front of the internal combustion engine but downstream of the
Im Kaltstartbereich K unterhalb des Temperaturschwellenwerts T1 ist der Ölkühler wie erwartet verschlossen, so dass die Temperatur T3 dem Verlauf der Zulauftemperatur T2 folgt und nur minimal unterhalb deren Wert liegt, aufgrund der vorstehend erwähnten Abstrahleffekte des Kühlers 16.In the cold start range K below the temperature threshold value T1, the oil cooler is closed, as expected, so that the temperature T3 follows the course of the inlet temperature T2 and is only slightly below its value, due to the above-mentioned radiation effects of the cooler 16.
Bei Erreichen und Überschreiten des Temperaturschwellenwerts T1 sollte das Stellglied des Ölthermostats 10 den ersten Ausgang 12 schrittweise öffnen. Bei einem normalfunktionierenden Ölthermostat würde sich der Verlauf ergeben, der mit der strichgepunkteten Linie T3.2 gekennzeichnet ist. Hierbei erhöht sich die Temperaturdifferenz ΔT=T2-T3.2 schrittweise.When the temperature threshold value T1 is reached and exceeded, the actuator of the
In
Im Rahmen der Erfindung wurde jedoch festgestellt, dass der Temperaturverlauf T3.1 bei einem Ölthermostat 10 beobachtet werden kann, dessen Stellglied bereits ein beginnendes Klemmverhalten oder ein leichtes Hakeln aufzeigt, so dass das Stellglied anfänglich im Bereich Z2 "klemmt" und sich erst zu einem späteren Zeitpunkt "losreißt" und sprunghaft in die komplette Offenstellung springt. Ein derartiges Klemmverhalten deutet auf ein zukünftiges vollständiges Verklemmen des Ölthermostats 10 hin.In the context of the invention, however, it was found that the temperature profile T3.1 can be observed in an
Gemäß dieser Variante erkennt die Auswerteeinrichtung 40 ein solches Fehlverhalten an dem Anstieg der Temperaturdifferenz ΔT, wenn der Anstieg der Temperaturdifferenz langsamer verläuft als ein vorgegebener Soll-Anstieg der Temperaturdifferenz. Mit anderen Worten wird der zeitliche Verlauf der Temperaturdifferenz erfasst. Wenn dieser weniger stark als ein vorgegebener Soll-Anstieg ist, der in Form einer experimentell bestimmten Kennlinie in der Auswerteeinrichtung 40 hinterlegt ist, wird eine Fehlfunktion des Ölthermostats 10 detektiert. Eine Möglichkeit zur Feststellung einer Fehlfunktion ist hierbei, einen Mindestwert für die Temperaturdifferenz aus T2 und T3 vorzugeben, die nach Überschreiten der Öffnungstemperatur T1 nach Ablauf einer vorgegebenen Reaktionszeit erreicht werden muss. Ist die gemessene Temperaturdifferenz nach Ablauf der vorgegebenen Reaktionszeit kleiner als der Mindestwert für die Temperaturdifferenz, liegt eine Fehlfunktion vor.According to this variant, the
Erkennt die Auswerteeinrichtung 40 somit einen der in den
Ferner ist darauf hinzuweisen, dass industrialisierte Thermostate bereits im Neuzustand einer Stelltemperatur-Toleranz unterliegen können. Diese kann in der Auswerteeinheit grundsätzlich berücksichtigt werden, beispielsweise werden bei kontinuierlicher Verschleißzunahme des Thermostats die definierten Temperaturgrenzen T1 und T1*, die zu einer Bewegung des Stellmechanismus führen, zunehmend häufiger gerissen bzw. verschoben. In der Auswerteeinheit können daher Berechnungsabfolgen aktiv sein und Kennfelder hinterlegt sein, die die definierten Temperaturgrenzen T1 und T1* und/oder die Schwellenwerte ΔT1 und ΔT2 für die Überwachungsvarianten der
In
Der durch den Drucksensor 15 gemessene zeitliche Druckverlauf ist mit der Kurve P dargestellt. Der Druckverlauf P beschreibt den Verlauf eines normal funktionierenden Ölthermostats 10. In den Temperaturbereichen der Zulauftemperatur T2 unterhalb von T1 weist der Druckverlauf im Wesentlichen den Wert P1 auf und in den Bereichen, in denen die Zulauftemperatur oberhalb des Werts T1* liegt, den Wert P2. Hierbei ist P2 im Wesentlichen etwas höher als P1, da der Ölkühler 16 einen höheren Strömungswiderstand als die Bypass-Leitung 18 hat und somit zu erhöhten Druckwerten P2 führt. Im Übergangsbereich zwischen T1 und T1* sind jedoch beide Leitungen zumindest teilweise geöffnet, so dass der Strömungswiderstand in diesem Bereich am geringsten ist. Dies führt zu einem negativen Druckpeak ΔP im Bereich des zeitlichen Druckverlaufs zwischen T1 und T1*.The curve P shows the pressure profile over time measured by the
Wird ein derartiger Druckpeak ΔP im Bereich des zeitlichen Druckverlaufs im Temperaturübergangsbereich 50 zwischen T1 und T1* gemessen, kann daraus gefolgert werden, dass das Thermostatventil 10 ordnungsgemäß arbeitet. Erkennt jedoch die Auswerteeinrichtung 40 anhand des gemessenen Druckverlaufs P, dass in dem Temperaturübergangsbereich 50 kein derartiger Druckausschlag ΔP auftritt, kann daraus gefolgert werden, dass sich das Stellglied des Ölthermostats 10 nicht erwartungsgemäß bewegt hat und somit eine Fehlfunktion vorliegt.If such a pressure peak ΔP is measured in the area of the pressure profile over time in the
Statt des Drucksensors 15, der zwischen dem Ölthermostat und Ölkühler 16 angeordnet ist, kann der Druckverlauf auch beispielsweise mit dem Drucksensor 25 gemessen werden, der nach dem Ölfilter angeordnet ist. In diesem Fall unterscheidet sich der Soll-Druckverlauf von dem in
Die Temperatursensoren 4, 14a, 14b und 24 und die Drucksensoren 15 und 25 wurden zur Vereinfachung der Darstellung alle gleichzeitig in
Weitere Ausgestaltungsformen der Erfindung werden nachfolgend mit
Mit dem Bezugszeichen 14a und 15 sind wiederum die in
Statt des kombinierten Öldruck- und Temperatursensors 14a, 15 kann die Funktion des Ölthermostats auch direkt mittels eines Wegsensors 81 überwacht werden, bei dem eine Koppelstange 82 direkt mechanisch mit dem Stellglied 10b des Ölthermostats 10 bewegungsgekoppelt ist. Gemäß dieser Ausführungsvariante wird die Bewegung des Stellglieds 10b des Ölthermostats 10 somit direkt durch den Wegsensor 81 erfasst und über eine Ausgangsleitung 83 vom Wegsensor 81 an die Auswerteeinrichtung 40 ausgegeben. Gemäß dieser Ausführungsvariante ist die Auswerteeinrichtung 40 ausgeführt, eine Fehlfunktion zu diagnostizieren, wenn bei Überschreiten der Öffnungstemperatur T1 oder allgemein bei Erreichen des Temperaturbereichs zwischen T1 und T1* keine Bewegung des Stellglieds 10b erfolgt.Instead of the combined oil pressure and
Hierbei ist ein Schaltkontakt des Schaltkreises 80 an einem Ende des Stellglieds 10b angeordnet und erfasst eine Bewegung eines Ventiltellers 10c des Stellglieds 10b, wenn dieses sich bewegt, um einen Ausgang des Ölthermostats 10 zu verschließen oder zu öffnen, und dabei in Kontakt oder außer Kontakt zu dem Schaltkontakt kommt.Here, a switching contact of the switching
Ferner ist der integrierte Schaltkreis 80 ausgeführt, seine Versorgungenergie mittels eines sogenannten Energie-Harvesting-Schaltkreises der Ölwärme zu entziehen. Derartige Energie-Harvesting-Schaltkreise sind an sich aus dem Stand der Technik bekannt. Ferner ist der Schaltkreis 80 ausgebildet, seine Messsignale drahtlos mittels einer Nahfeldfunkübertragung an die Auswerteeinrichtung 40 zu übermitteln. Dadurch kann der integrierte Schaltkreis komplett von dem Ölthermostat 10 umkapseit werden, so dass keine zusätzlichen Abdichtungselemente, Signalleitungen oder Energieversorgungsleitungen vorgesehen sein müssen.Furthermore, the
In
Im Unterschied zu den Varianten der
Gemäß einer ersten Variante umfasst die Sensoreinrichtung einen elektrischen Schwingkreis mit einer Spule 76, wobei die Spule 76 von außen am Gehäuse 10a des Ölthermostats 10 angeordnet ist. Hierbei wird die Spule so angeordnet, dass eine Bewegung des Stellglieds 10b des Ölthermostats 10, das magnetisch ausgeführt ist, die Induktivität der Spule 76 und damit eine Schwingungsfrequenz des Schwingkreises verändert. Das Messsignal des Schwingkreises mit der Spule 76 wird über eine Signalleitung 76a an die Auswerteeinrichtung 40 übermittelt.According to a first variant, the sensor device comprises an electrical oscillating circuit with a
Somit kann die Auswerteeinrichtung 40 wiederum die Funktion des Ölthermostats 10 überwachen, indem sie anhand einer der vorgenannten Möglichkeiten zur Bestimmung eines ersten Parameters, aus dem der Soll-Betrieb des Ölthermostats ableitbar ist, bestimmt, wann sich ein Stellglied des Ölthermostats 10 bewegen müsste. Anhand der erfassten Frequenz des Schwingkreises kann die Auswerteeinrichtung 40 ferner ermitteln, ob eine erwartete Bewegung des Stellglieds 10b zu der erwarteten Zeit tatsächlich stattfindet oder ob beispielsweise das Stellglied klemmt und somit keine Änderung der Schwingungsfrequenz messbar ist.Thus, the
Eine weitere Möglichkeit zur berührungslosen Erkennung der Bewegung des Stellglieds 10b des Ölthermostats 10 ist, die Sensoreinrichtung so auszuführen, dass eine Senderspule 74 und eine Empfängerspule 75 auf jeweils gegenüberliegenden Seiten von außen am Ölthermostatgehäuse 10b oder in dessen Nähe angeordnet sind. Eine Bewegung des magnetischen Stellglieds 10b des Ölthermostats 10 verändert dann ein von der Senderspule 74 in der Empfängerspule 75 induziertes Signal, das über eine Signalleitung 75a an die Auswerteeinrichtung 40 übermittelt wird. Diese Veränderung kann wiederum von der Auswerteeinrichtung 40 diagnostiziert werden, so dass das Vorhandensein einer solchen Veränderung des mit der Empfängerspule empfangenen Signals entsprechend eine normale Funktion des Ölthermostats anzeigt. Wird zu der erwarteten Zeit gemäß Soll-Betrieb keine solche Veränderung des mit der Empfängerspule empfangenen Signals gemessen, liegt eine Fehlfunktion des Ölthermostats 10 vor.A further possibility for non-contact detection of the movement of the actuator 10b of the
- 11
- Ölkreislaufoil cycle
- 22
- Ölwannesump
- 2a2a
- Ölsumpfoil sump
- 33
- Ölstandssondeoil level probe
- 44
- ÖlsumpftemperatursensorOil sump temperature sensor
- 55
- Zulaufleitunginlet line
- 66
- Ölpumpeoil pump
- 77
- Überdruckventilpressure relief valve
- 88th
- Rücklaufsperrventilnon-return valve
- 99
- Ölsteuerleitungoil control line
- 1010
- ÖlthermostatventilOil thermostatic valve
- 10a10a
- ÖlthermostatventilgehäuseOil thermostatic valve body
- 10b10b
- Stellgliedactuator
- 10c10c
- Ventiltellervalve plate
- 1111
- EingangEntry
- 1212
- Erster AusgangFirst exit
- 1313
- Zweiter AusgangSecond exit
- 14a14a
- Öltemperatursensoroil temperature sensor
- 14b14b
- Öltemperatursensoroil temperature sensor
- 1515
- Öldrucksensoroil pressure sensor
- 1616
- Ölkühleroil cooler
- 1717
- Erster StrömungszweigFirst flow branch
- 1818
- Bypass-Strömungszweigbypass flow branch
- 1919
- Ölleitungoil line
- 2020
- Ölfilteroil filter
- 2121
- Filterserviceventilfilter service valve
- 2222
- Filterumgehungsventilfilter bypass valve
- 2323
- Siphon im ÖlfilterkopfSiphon in the oil filter head
- 2424
- Öltemperatursensoroil temperature sensor
- 2525
- Ölzufuhr zur BrennkraftmaschineOil supply to the internal combustion engine
- 2626
- Ölleitungoil line
- 2727
- Ölmoduloil module
- 4040
- Auswerteeinrichtungevaluation device
- 4141
- Signaleingangsleitungsignal input line
- 4242
- Signalausgangsleitungsignal output line
- 5050
- Temperaturübergangsbereichtemperature transition range
- 7070
- Kühlwasserzuführleitungcooling water supply line
- 7171
- Kühlwasserumströmungsbereichcooling water flow area
- 7272
- Kühlwasserabführleitungcooling water discharge line
- 7373
- Ölrückführungoil return
- 7474
- Sendespuletransmitter coil
- 7575
- Empfängerspulereceiver coil
- 75a75a
- Empfängerspulensignalleitungenreceiver coil signal lines
- 7676
- Schwingkreisresonant circuit
- 76a76a
- Schwingkreissignalleitungenresonant circuit signal lines
- 8080
- Integrierter Schaltkreisintegrated circuit
- 8181
- Wegsensordisplacement sensor
- 8282
- Koppelstangeconnecting rod
- 8383
- Signalleitungensignal lines
- BB
- Bereich einer betriebswarmen BeharrungRange of an operating temperature persistence
- KK
- Kaltstartphasecold start phase
- PP
- Druckverlaufpressure curve
- ΔPΔP
- Druckausschlag (Peak)pressure rash (peak)
- T1T1
- Erster TemperaturschwellenwertFirst temperature threshold
- T1*T1*
- Zweiter TemperaturschwellenwertSecond temperature threshold
- T2T2
- Zulauftemperaturinlet temperature
- T3T3
- Zweite ÖltemperaturSecond oil temperature
- T3.1T3.1
- Temperaturgradient bei DefektverhaltenTemperature gradient in defect behavior
- T3.2T3.2
- Temperaturgradient bei normalem VerhaltenTemperature gradient with normal behavior
- ΔTΔT
- Temperaturdifferenztemperature difference
- ΔT1ΔT1
- Erster SchwellenwertFirst Threshold
- ΔT2ΔT2
- Zweiter SchwellenwertSecond threshold
- Z1Z1
- Reaktionszeitreaction time
- Z2Z2
- Thermostatsöffnungsbereichthermostat opening range
Claims (15)
- Apparatus for monitoring an oil thermostat (10) arranged in an oil circuit of an internal combustion engine, wherein the oil thermostat (10) is designed to supply an oil flow either to a first flow branch (17) in which an oil cooler (16) is arranged and/or to a bypass flow branch (18) depending on an admission temperature (T2) of the oil flow supplied to the oil thermostat, wherein a first outlet (12) of the oil thermostat (10), which outlet is assigned to the first flow branch, is closed when the admission temperature (T2) lies below a first temperature threshold value (T1), wherein the apparatus comprises:a) a sensor device which is designed to determine at least one first parameter by means of which a current desired operation of the oil thermostat (10) can be derived, and to determine at least one second parameter by means of which a current actual operation of the oil thermostat (10) can be derived; andb) an evaluation device (40) which is designed, depending on the first parameter and the second parameter, to identify an occurrence of a malfunction of the oil thermostat (10),wherein the sensor device is designed to measure the admission temperature (T2) of the oil as the first parameter, wherein preferably the oil sump temperature is measured as the admission temperature (T2),characterizeda) in that the sensor device is designed to measure a second oil temperature (T3) downstream of the oil cooler and upstream of the internal combustion engine and to determine a temperature difference (ΔT) from the admission temperature (T2) minus the second oil temperature (T3) as the second parameter; andb) in that the evaluation device identifies the occurrence of a malfunction of the oil thermostat,b1) when the admission temperature (T2) lies below the first temperature threshold value (T1), at least one predetermined reaction period (Z1) has elapsed since the admission temperature (T2) has been below the first temperature threshold value (T1), and the temperature difference (ΔT) is greater than a first threshold value (ΔT1); and/orb2) when the admission temperature (T2) is above the first temperature threshold value (T1) at least one predetermined reaction period (Z1) has elapsed since the admission temperature (T2) has been above the first temperature threshold value (T1), and the temperature difference (ΔT) is smaller than a second threshold value (ΔT2) ; and/orb3) when, after the first temperature threshold value (T1) is exceeded by the admission temperature (T2), an increase of the temperature difference (ΔT) proceeds more slowly than a predetermined desired increase of the temperature difference (ΔT).
- Apparatus according to Claim 1, characterized by a temperature sensor for measuring the second oil temperature (T3),a) which is arranged upstream of a junction of the first flow branch (17) and of the bypass flow branch (18) or downstream of an oil filter (20) arranged before the internal combustion engine; and/orb) which is designed as a combined pressure and temperature sensor (24, 25); and/orc) which is integrated in an oil filter head.
- Apparatus according to Claim 1, characterizeda) in that the sensor device is designed to measure, as the second parameter, an oil pressure progression (P) at a pressure measurement point which is arranged downstream of the first outlet (12) of the oil thermostat (10) and upstream with respect to the internal combustion engine; andb) in that the evaluation device identifies a malfunction of the oil thermostat (10) when the measured progression of the oil pressure (P) does not indicate any pressure swing (ΔP) within a range (50) of the admission temperature (T2) that lies between the first oil temperature threshold value (T1) and a second temperature threshold value (T1*), wherein the second temperature threshold value (T1*) lies above the first temperature threshold value (T1) and specifies a temperature threshold above which a second outlet (13) of the oil thermostat (10), which outlet is assigned to the bypass flow branch (18), is completely closed.
- Apparatus according to Claim 3, characterizeda) in that the pressure measurement point is arranged in the first flow branch (17) between the first outlet (12) of the oil thermostat (10) and the oil cooler (16), and in that the pressure swing (ΔP) is a negative peak; and/orb) in that the pressure measurement point is arranged downstream of the oil cooler (16) and after a junction of the first flow branch (17) and of the bypass flow branch (18), and in that the pressure swing is a positive peak.
- Apparatus according to Claim 1, characterized in that the following is established as the first parameter:a) a cooling water temperature; and/orb) an operating state of the vehicle, in particular whether a cold start or whether a journey at full load is carried out.
- Apparatus according to Claim 1 or 5, characterizeda) in that a gradient of the admission temperature (T2) of the oil, preferably a gradient of the oil sump temperature, is determined as the second parameter; andb) in that the evaluation device establishes, depending on the determined value of the first parameter, a predetermined and stored desired characteristic curve of the gradient of the admission temperature (T2) and identifies a malfunction of the oil thermostat when the measured gradient of the admission temperature does not correspond to the desired characteristic curve.
- Apparatus according to Claim 1 or 5, characterizeda) in that, as the second parameter, an oil temperature is measured at a measurement point which is arranged in the first flow branch (17) upstream with respect to the oil cooler (16); andb) in that the evaluation device identifies a malfunction of the oil thermostat when the measured oil temperature in accordance with the second parameter remains substantially unchanged since, in accordance with the determined first parameter, the first outlet (12) would have had to be opened or closed.
- Apparatus according to Claim 1 or 5, characterizeda) in that the sensor device is designed to detect a position and/or a movement of a final control element (10b) of the oil thermostat (10) as the second parameter; andb) in that the evaluation device is designed to identify the malfunction of the oil thermostat (10) with reference to the detected position and/or movement of the final control element (10b).
- Apparatus according to Claim 8, characterized in that the malfunction of the oil thermostat (10) is identifieda) when no movement of the final control element (10b) is detected within a predetermined oil temperature range or cooling water temperature range; and/orb) when, during a cold start, the final control element (10b) is in a position in which the first outlet (12) is opened; and/orc) when, during a driving mode at full load, the final control element (10b) is in a position in which the first outlet (12) is closed.
- Apparatus according to Claim 8 or 9, characterized in that the sensor device comprises a displacement sensor (81) which is mechanically coupled in terms of movement to the final control element (10b).
- Apparatus according to Claim 8 or 9, characterizeda) in that the sensor device is designed as an electric oscillating circuit with a coil (76), wherein the coil (76) is arranged from the outside on or in the vicinity of the oil thermostat (10) in such a manner that a movement of the final control element (10b) of the oil thermostat (10) changes the inductance of the coil (76) and therefore an oscillation frequency of the oscillating circuit; orb) in that the sensor device has a transmitter coil (74) and a receiver coil (75) which are each arranged on opposite sides from the outside on or in the vicinity of the oil thermostat (10), and therefore a movement of the final control element (10b) of the oil thermostat changes a signal induced in the receiver coil (75) by the transmitter coil (74).
- Apparatus according to Claim 11, characterized in that the apparatus is designed as a mobile test apparatus for workshop use, comprising fastening means in order to arrange the sensor device from the outside on the oil thermostat temporarily for a measurement operation.
- Apparatus according to Claim 8 or 9, characterized in that the sensor device is designed as a switching circuit (80) which is integrated in the oil thermostat and is designeda) to detect a position and/or movement of the final control element (10b) of the oil thermostat (10) by means of integrated switching contacts;b) to extract its supply energy from the oil heat by means of an energy-harvesting switching circuit; andc) to transmit a measurement signal wirelessly, preferably by means of a close range radio transmission, to the evaluation device.
- Apparatus according to one of the preceding claims, characterized in that the oil thermostat (10) is a sleeve valve oil thermostat or an expansion element oil thermostat, in particular a wax expansion oil thermostat.
- Vehicle, in particular commercial vehicle, with an apparatus according to one of the preceding claims.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102014016307.5A DE102014016307A1 (en) | 2014-11-06 | 2014-11-06 | Device for monitoring an oil thermostat |
PCT/EP2015/002214 WO2016070993A1 (en) | 2014-11-06 | 2015-11-04 | Apparatus for monitoring an oil thermostat |
Publications (2)
Publication Number | Publication Date |
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EP3215723A1 EP3215723A1 (en) | 2017-09-13 |
EP3215723B1 true EP3215723B1 (en) | 2022-09-28 |
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EP15794465.3A Active EP3215723B1 (en) | 2014-11-06 | 2015-11-04 | Apparatus for monitoring an oil thermostat |
Country Status (6)
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US (1) | US10287934B2 (en) |
EP (1) | EP3215723B1 (en) |
CN (1) | CN107075992B (en) |
DE (1) | DE102014016307A1 (en) |
RU (1) | RU2702208C2 (en) |
WO (1) | WO2016070993A1 (en) |
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US10920628B2 (en) * | 2015-08-25 | 2021-02-16 | Cummins Inc. | Cooling assembly for a filter head of an engine |
DE102016208153A1 (en) * | 2016-05-12 | 2017-11-16 | Friedrich-Alexander-Universität Erlangen-Nürnberg | Measuring arrangement for lubricating oil and measuring methods |
US11598230B2 (en) * | 2017-12-29 | 2023-03-07 | Volvo Truck Corporation | Fluid circuit and a process for controlling a flow of fluid supplied to at least one equipment |
DE102018125256B4 (en) * | 2018-10-12 | 2020-10-15 | Single Holding GmbH | Diagnostic procedures for temperature control devices |
CN113494347B (en) * | 2021-08-09 | 2022-10-18 | 一汽解放汽车有限公司 | Control method of engine cooling system |
CN115063045B (en) * | 2022-08-08 | 2022-11-15 | 淄博威世能净油设备有限公司 | Oil purifier operating efficiency evaluation system based on data processing |
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2014
- 2014-11-06 DE DE102014016307.5A patent/DE102014016307A1/en active Pending
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2015
- 2015-11-04 EP EP15794465.3A patent/EP3215723B1/en active Active
- 2015-11-04 RU RU2017119467A patent/RU2702208C2/en active
- 2015-11-04 US US15/524,838 patent/US10287934B2/en active Active
- 2015-11-04 CN CN201580060309.2A patent/CN107075992B/en active Active
- 2015-11-04 WO PCT/EP2015/002214 patent/WO2016070993A1/en active Application Filing
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EP0736703A1 (en) * | 1995-04-05 | 1996-10-09 | Bayerische Motoren Werke Aktiengesellschaft, Patentabteilung AJ-3 | Device for influencing the oil temperature in vehicle transmissions |
Also Published As
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BR112017009549A2 (en) | 2019-05-14 |
US20170342877A1 (en) | 2017-11-30 |
RU2017119467A (en) | 2018-12-06 |
CN107075992B (en) | 2019-11-26 |
RU2017119467A3 (en) | 2019-04-01 |
US10287934B2 (en) | 2019-05-14 |
CN107075992A (en) | 2017-08-18 |
EP3215723A1 (en) | 2017-09-13 |
WO2016070993A1 (en) | 2016-05-12 |
DE102014016307A1 (en) | 2016-05-12 |
RU2702208C2 (en) | 2019-10-04 |
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